A diamond anti-counterfeiting mark, a manufacturing method and a decoding method thereof

Abstract

The application discloses a diamond anti-counterfeiting mark and a manufacturing method and a decoding method thereof. The manufacturing method comprises the following steps: demarcating a bar code area on the surface of a diamond substrate, and dividing the bar code area into a plurality of encoding units along a preset direction; controlling a femtosecond laser to process grating structures with different grating periods on the encoding units; wherein the different grating structures correspond to different structural colors; establishing an encoding mapping relationship between the grating structures and the structural colors of the encoding units, and taking the structural color sequence of all the encoding units as a unique anti-counterfeiting ID; determining the structural color corresponding to each encoding unit according to the unique anti-counterfeiting ID, and then determining the grating period corresponding to each encoding unit in combination with the encoding mapping relationship. The application generates a structural color sequence as an anti-counterfeiting ID by processing a multi-period grating through a femtosecond laser, and solves the problems of easy imitation and the need for professional equipment identification in the prior art.

Description

Technical Field

[0001] This application relates to the field of diamond processing technology, and in particular to a diamond anti-counterfeiting mark and its manufacturing and decoding methods. Background Technology

[0002] With the rapid development and large-scale production of chemical vapor deposition (CVD) synthetic diamond technology, the differences between synthetic diamonds and natural diamonds in terms of physical properties and optical appearance are becoming increasingly smaller. Therefore, the identification, authentication, and full-chain traceability of diamonds have become core necessities for the jewelry industry. As a high-value commodity, the identification of diamonds directly relates to the legitimate rights and interests of consumers and the market order of the entire industry.

[0003] Currently, the most widely used diamond anti-counterfeiting technologies in the industry mainly include fluorescent marking technology and nanoparticle embedding, which to some extent enable diamond identification.

[0004] However, existing diamond anti-counterfeiting methods still have limitations. Some markings are easily physically removed or tampered with, resulting in insufficient anti-counterfeiting durability. Furthermore, the identification and verification of most anti-counterfeiting marks require specialized instruments and equipment, such as fluorescence microscopes, spectrometers, or high-magnification magnifying glasses. Ordinary consumers find it difficult to quickly and accurately determine authenticity at the point of purchase, which greatly limits the practical application effect of anti-counterfeiting technology. Summary of the Invention

[0005] This application provides a diamond anti-counterfeiting label and its manufacturing and decoding methods. By controlling a femtosecond laser to process grating structures of different periods on multiple coding units on the diamond surface to generate different structural colors, the structural color sequence is used as a unique anti-counterfeiting ID. This solves the technical problems of existing diamond anti-counterfeiting technologies being easily counterfeited or tampered with, and requiring professional equipment for identification.

[0006] The first aspect of this application provides a method for producing a diamond anti-counterfeiting label, the method comprising:

[0007] A barcode area is defined on the surface of a diamond matrix, and the barcode area is divided into several coding units along a preset direction; By controlling a femtosecond laser, grating structures with different grating periods are fabricated on each of the coding units; wherein, different grating structures correspond to different structural colors; Establish the encoding mapping relationship between the grating structure and the structural color of each encoding unit, and use the structural color sequence of all encoding units as a unique anti-counterfeiting ID; Based on the unique anti-counterfeiting ID, the structural color corresponding to each of the coding units is determined, and then the grating period corresponding to each of the coding units is determined by combining the coding mapping relationship.

[0008] Optionally, establishing the encoding mapping relationship between the grating structure and the structural color of each encoding unit, and using the structural color sequence of all encoding units as a unique anti-counterfeiting ID, includes: Each of the coding units is illuminated with white light and an image is acquired to obtain the structural color presented by each of the coding units; The grating period of each coding unit is summed with the structural color to obtain the coding mapping relationship; Based on the arrangement order of each coding unit in the barcode area, the structural colors of each coding unit are combined sequentially to form a structural color sequence, and the structural color sequence is used as a unique anti-counterfeiting ID.

[0009] Optionally, the step of sequentially combining the structural colors of each of the coding units according to their arrangement order in the barcode area to form a structural color sequence, and using this structural color sequence as the unique anti-counterfeiting ID, includes: The arrangement order of the structural colors is determined based on the position number of each coding unit in the barcode area; The structural color of each coding unit is converted into a corresponding coding symbol, and there is a one-to-one correspondence between the coding symbol and the structural color. According to the arrangement order, the coded symbols are sequentially concatenated to obtain a coded sequence, which serves as the unique anti-counterfeiting ID of the diamond.

[0010] Optionally, the step of defining a barcode area on the surface of the diamond matrix and dividing the barcode area into several coding units along a preset direction includes: A continuous area is delineated on the surface of the diamond matrix as a barcode area, and the start and end boundaries of the barcode area are determined. The barcode area is divided along a preset direction from the starting boundary to the ending boundary to obtain several encoding units; Each of the coding units is assigned a sequential index to determine the arrangement order.

[0011] Optionally, the step of controlling a femtosecond laser to fabricate grating structures with different grating periods on each of the coding units, wherein different grating structures correspond to different structural colors, includes: Each coding unit is scanned according to preset laser parameters. Different target grating periods are set for different coding units by changing the pulse energy or scanning speed. A grating structure with a corresponding period is formed in each coding unit along the preset scanning path, so that different coding units obtain different structural colors.

[0012] Optionally, determining the structural color corresponding to each encoding unit based on the unique anti-counterfeiting ID, and then determining the grating period corresponding to each encoding unit, includes: The unique anti-counterfeiting ID is parsed, and the structural color corresponding to each encoding unit is extracted according to the arrangement order of each encoding unit; Based on the encoding mapping relationship, query the grating period interval corresponding to each structural color; A target period value is selected within each grating period interval and used as the grating period corresponding to that coding unit.

[0013] Optionally, the manufacturing method further includes: after processing, performing optical detection on the structural color of each coding unit, and comparing the detected structural color with the structural color expected according to the coding mapping relationship; if the comparison result is inconsistent, the coding unit is reprocessed.

[0014] A second aspect of this application provides a method for decoding diamond anti-counterfeiting marks, the decoding method comprising: Obtain a pre-established encoding mapping relationship, which is used to associate the grating period with the structure color; Images of the barcode area are acquired by white light illumination, and the images are located and segmented to obtain the image areas corresponding to each coding unit; Color analysis is performed on the image regions corresponding to each coding unit, and the structural color of each coding unit is determined according to the coding mapping relationship. According to the arrangement order of each of the coding units, the structural colors of each coding unit are sequentially combined into a sequence, and the sequence is used as the decoded anti-counterfeiting ID.

[0015] The third aspect of this application provides a diamond anti-counterfeiting label, which is manufactured using the diamond anti-counterfeiting label manufacturing method described in any one of the first aspects.

[0016] Optionally, the diamond anti-counterfeiting mark includes a diamond substrate and a barcode area formed on its surface; The barcode area is divided into several coding units, each of which has a grating structure with a different period, so that each coding unit presents a different structural color under white light. The structural color sequence of all the encoded units is arranged in a preset order as the unique anti-counterfeiting ID of the diamond.

[0017] As can be seen from the above technical solutions, this application has the following advantages: By dividing the barcode area into multiple coding units and using femtosecond lasers to process grating structures of different periods on each unit to generate different structural colors, the structural color sequence serves as a unique anti-counterfeiting ID, meeting the needs of large-scale diamond anti-counterfeiting and traceability. Simultaneously, the grating structure is a permanent physical nanostructure on the diamond surface, which cannot be replicated by printing, coating, or chemical etching, and cannot be restored even after polishing, effectively solving the problem of existing markings being easily counterfeited or tampered with. Furthermore, this structural color can be initially identified with the naked eye under white light, and decoding can be completed using a regular mobile phone camera and an app, eliminating the need for professional equipment such as fluorescence microscopes and spectrometers, greatly lowering the barrier to on-site verification for consumers. Moreover, the grating structure is formed only at a nanometer-level depth on the surface, without affecting the diamond's clarity, weight, or other core qualities, providing stable anti-counterfeiting performance. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic flowchart illustrating an embodiment of the method for producing the diamond anti-counterfeiting label provided in this application; Figure 2 A flowchart illustrating an embodiment of the method for creating diamond anti-counterfeiting labels provided in this application, which establishes a coding mapping relationship; Figure 3 A flowchart illustrating an embodiment of the method for producing diamond anti-counterfeiting labels provided in this application, which defines the barcode area and divides the coding units; Figure 4 A flowchart illustrating an embodiment of the method for producing a diamond anti-counterfeiting label provided in this application, in which the grating period is determined based on a unique anti-counterfeiting ID; Figure 5 This is a flowchart illustrating an embodiment of the decoding method for diamond anti-counterfeiting labels provided in this application.

[0020] Figure 6 A schematic diagram of the structure of one embodiment of the diamond anti-counterfeiting label provided in this application. Detailed Implementation

[0021] It should be noted that the diamond anti-counterfeiting label, its manufacturing method, and its decoding method provided in this application can be widely used for anti-counterfeiting and traceability throughout the entire life cycle of natural diamonds, CVD synthetic diamonds, and lab-grown diamonds. In the diamond production process, manufacturers use femtosecond lasers to process barcode areas composed of multiple coded units on the girdle or table edge of the diamond. By controlling the grating period of each unit, different structural colors are presented, and the structural color sequence of all coded units serves as a unique anti-counterfeiting ID. This ID is then encrypted and stored in a blockchain system after being linked to information such as diamond weight, clarity, and production batch. At the point of purchase, consumers only need to use their mobile phone flashlight to illuminate the barcode area and open a dedicated app to photograph it. The app can automatically locate and segment the image, analyze the structural colors of each unit, and decode the anti-counterfeiting ID according to the built-in coding mapping relationship. After comparing it with the cloud database, the verification result and detailed diamond identity information are returned instantly. For high-value diamonds, two sets of barcodes with paired verification relationships can be processed on the girdle and culet, respectively. Even if criminals attempt to remove one set of markings by polishing, the other set of markings can still trigger an anomaly alarm, thus preventing partial tampering. In the secondary diamond market, buyers can trace the historical circulation record of the diamond through the same barcode verification method, ensuring transparent and secure transactions. This system covers the entire anti-counterfeiting needs of diamonds from production and distribution to end-user sales and secondary transactions.

[0022] This application first provides an embodiment of a method for producing diamond anti-counterfeiting labels; please refer to [link / reference]. Figure 1 , Figure 1 A flowchart illustrating an embodiment of the method for producing a diamond anti-counterfeiting label provided in this application, the embodiment including: S101. Delineate a barcode area on the surface of the diamond matrix and divide the barcode area into several coding units along a preset direction; The diamond matrix to be processed is selected. This matrix can be a natural diamond or a CVD synthetic diamond. The matrix is ​​typically already cut and polished, with clearly defined girdle facets, table facets, and culet facets. The operator uses a femtosecond laser processing platform with a microscope objective to mark a continuous, flat barcode area on the surface of the diamond matrix. The barcode area is usually chosen at the edge of the girdle facet or table facet because these areas are less prone to wear and tear. The length and width dimensions of the barcode area are determined based on the size of the diamond and the required coding capacity.

[0023] The barcode area is divided into several equally spaced coding units along a preset direction. During division, the positioning function of the laser processing platform is used to set the boundary coordinates of each coding unit, and the start and end boundaries are recorded. The width of each coding unit can be set according to the focused spot diameter of the femtosecond laser and the desired color differentiation, for example, set to 20μm to 100μm. After division, a sequential index is assigned to each coding unit to determine the arrangement order of the structural colors later. For example, on the girdle face of a 0.5ct CVD diamond, a barcode area with a length of 1.2mm and a width of 0.12mm is demarcated, divided equally along the length direction into 12 coding units, each unit with a width of 100μm, and assigned indices 1 to 12.

[0024] S102. By controlling the femtosecond laser, grating structures with different grating periods are fabricated on each coding unit; wherein, different grating structures correspond to different structural colors; Based on the desired structural color for each coding unit, the corresponding target grating period is looked up in a pre-established table of laser parameters and periods. For the current coding unit, the processing wavelength and pulse width of the femtosecond laser are set; by adjusting the pulse energy density or scanning speed, the grating period induced by the laser on the diamond surface is made to fall within the target period range. Higher pulse energy density or slower scanning speed generally results in a larger period.

[0025] Then, the coding unit is scanned along a preset scanning path. The scanning path typically uses a line-by-line filling method. The laser beam scans in a straight line along a first direction to form the first grating line, then moves one scanning interval along the vertical direction, and then performs a second scan in the opposite direction. This process is repeated until the entire coding unit area is covered. During the scanning process, the femtosecond laser undergoes nonlinear absorption with the diamond surface, forming transient plasma, which eventually self-organizes to form a periodic nanograting structure. For different coding units, the above parameter settings and scanning process are repeated, and by changing the pulse energy density or scanning speed, different units form different grating periods, thereby obtaining different structural colors. For example, for the coding unit of index 1, after processing 12 units in sequence, the barcode area presents a color stripe sequence: purple, blue, cyan, green, yellow, orange, red, dark red, purple, blue, cyan, green.

[0026] S103. Establish the coding mapping relationship between the grating structure and the structural color of each coding unit, and use the structural color sequence of all coding units as a unique anti-counterfeiting ID; After laser processing of all coding units is completed, the processing results need to be inspected and encoded. First, each coding unit is illuminated with white light and images are acquired: a white LED light source illuminates the barcode area at a preset angle, and a high-resolution camera captures a color image at the corresponding viewing angle. Since different periods of the grating structure exhibit different colors under white light diffraction, each coding unit in the image will display a distinct structural color. Then, the structural color information of each coding unit is extracted from the image. For example, the average values ​​of red, green, and blue for each unit region are obtained through image processing algorithms, and these average values ​​are converted into a hue, saturation, and brightness color space. The color category is determined based on the hue value. Simultaneously, the actual laser parameters used in processing each coding unit and the measured grating period are recorded.

[0027] The grating period of each coding unit is associated with the detected structural color to form a mapping table between period and color, which is the coding mapping relationship. Finally, according to the arrangement order of the coding units in the barcode area, the structural colors of all units are combined into a string sequence. For example, the color sequence of the above 12 units is "purple-blue-cyan-green-yellow-orange-red-deep red-purple-blue-cyan-green", which can be abbreviated as "VBCGYORXVBCG", where V is purple, B is blue, C is cyan, G is green, Y is yellow, O is orange, R is red, and X is deep red. This string sequence serves as the unique anti-counterfeiting ID of the diamond.

[0028] S104. Based on the unique anti-counterfeiting ID, determine the structural color corresponding to each coding unit, and then determine the grating period corresponding to each coding unit by combining the coding mapping relationship.

[0029] From the generated unique anti-counterfeiting IDs, the structural color symbols corresponding to each position are parsed sequentially according to their arrangement. Based on the established encoding mapping relationship, the grating period range corresponding to each structural color symbol is queried. For example, V corresponds to 150–200 nm, B corresponds to 200–260 nm, C corresponds to 260–320 nm, and so on. Within each range, a specific target period value can be selected as the theoretical grating period of that encoding unit.

[0030] By comparing the theoretical target cycle with the actual processing measurement cycle, if the deviation exceeds the allowable range, the coded unit can be determined to be unqualified, triggering reprocessing or marking it as scrap. Simultaneously, it provides a theoretical benchmark for subsequent database comparison during decoding, ensuring the uniqueness and verifiability of the anti-counterfeiting ID.

[0031] After processing, the structural color of each coding unit can be optically detected and compared with the expected structural color based on the coding mapping relationship. If the comparison results are inconsistent, the coding unit is reprocessed. Specifically, real-time images of the barcode area are captured using white light illumination and a camera. The structural color of each coding unit is automatically obtained through an image recognition algorithm, and its matching degree with the expected color is calculated. If the color difference is less than a preset threshold, it is considered qualified; otherwise, the unit is judged to be abnormally processed and needs to be reprocessed or scrapped.

[0032] In this embodiment, by dividing the barcode area into multiple coding units and using femtosecond lasers to process grating structures with different periods on each unit to generate different structural colors, the structural color sequence is used as a unique anti-counterfeiting ID, which can meet the needs of large-scale diamond anti-counterfeiting and traceability. At the same time, the grating structure is a permanent physical nanostructure on the diamond surface, which cannot be replicated by printing, coating or chemical etching, and cannot be restored even if polished off, effectively solving the problem that existing markings are easily counterfeited or tampered with. In addition, the structural color can be initially identified by the naked eye under white light, and can be decoded with ordinary mobile phone cameras and APPs, without the need for professional equipment such as fluorescence microscopes and spectrometers, which greatly reduces the threshold for consumers to verify on-site. Moreover, the grating structure is only formed at a nanometer depth on the surface and does not affect the core quality of the diamond such as clarity and weight, and has stable anti-counterfeiting performance.

[0033] A coding mapping relationship is established between the raster structure and structural color of each coding unit, and the structural color sequence of all coding units is used as a unique anti-counterfeiting ID. The establishment of the coding mapping relationship and the generation of the unique anti-counterfeiting ID are described in detail below. Please refer to [link / reference]. Figure 2 , Figure 2 A flowchart illustrating an embodiment of the method for producing diamond anti-counterfeiting labels provided in this application, which establishes a coding mapping relationship, includes: S201. Illuminate each coding unit with white light and acquire images to obtain the structural color presented by each coding unit; After femtosecond laser processing, the individual coding units within the barcode area of ​​the diamond substrate have formed grating structures with different periods. To obtain the actual structural color of each coding unit, standardized optical inspection is required. Specifically, the diamond substrate is placed on an optical inspection platform, and a white LED light source is used to illuminate the barcode area at a preset incident angle. Simultaneously, a high-resolution color camera or industrial camera, equipped with a macro lens, is set at a preset observation angle to clearly image each individual coding unit.

[0034] After fixing the lighting and viewing angle, images are acquired of the barcode area. Due to the diffraction effect of white light on the grating structure with different periods, each coding unit will exhibit a structural color of a specific wavelength. In the acquired color image, each coding unit corresponds to a rectangular image block with uniform color and clear boundaries. To improve the robustness of color recognition, each coding unit area can be imaged multiple times, for example, with different exposure times or different white balance settings, and the image with the highest color saturation and the least noise is selected as the analysis object.

[0035] S202. Summarize the grating period and structural color of each coding unit to obtain the coding mapping relationship; After obtaining the structural color of each coding unit, this color information needs to be correlated and summarized with the grating period of the corresponding unit to form a coding mapping relationship that can be queried and reverse-mapped. The actual laser parameters used for each coding unit and the grating period value obtained through online or offline detection are retrieved from the process records of the laser processing system. The grating period can be obtained by local measurement of the sample using an atomic force microscope or scanning electron microscope, or it can be calculated based on the calibration curve of laser processing parameters and the period.

[0036] The acquired structured color images are processed to extract the color features of each coding unit. The mean values ​​of red, green, and blue are calculated for the image region of each coding unit. These values ​​are then converted to a hue-saturation-lightness color space to obtain the hue value representing the color of that unit. The color category can be determined by the hue value; for example, a hue value between 0° and 30° corresponds to red, 30° to 60° corresponds to orange, and so on. The period value of each coding unit is mapped one-to-one with the color category obtained from image analysis. The mapping relationships of all coding units are summarized in a table, i.e., the coding mapping relationship.

[0037] S203. Determine the arrangement order of the structural colors according to the position number of each coding unit in the barcode area; After obtaining the structural color of each coding unit, these colors need to be organized into a sequence according to their spatial arrangement in the barcode area. Specifically, the position number of each coding unit is read from the coordinate record of the processing platform. The position number can be either a physical coordinate order or a user-defined logical order. Following the ascending order of the numbers, the structural color corresponding to each number is extracted, forming an ordered color list. For example, number 1 corresponds to purple, number 2 to blue, number 3 to cyan, and so on, with number 12 corresponding to green. This order directly determines the string sequence of the final anti-counterfeiting ID, so it is essential to ensure that the position numbers match the spatial arrangement of the coding units. To verify the correctness of the order, morphological analysis can be performed on the image of the barcode area during image processing to identify the starting boundary and align it with number 1. If a misalignment occurs, the number mapping is readjusted until the image order perfectly matches the record order.

[0038] S204. Convert the structural color of each coding unit into the corresponding coding symbol. There is a one-to-one correspondence between the coding symbol and the structural color. After obtaining the structural color and its arrangement order for each coded unit, the color names described in natural language need to be converted into concise, standardized coded symbols for easy storage, transmission, and comparison. The coded symbols typically use a single uppercase letter, number, or a combination of both. Each structural color uniquely corresponds to one coded symbol, and this symbol is globally fixed throughout the entire anti-counterfeiting system.

[0039] Specifically, a mapping table between structural colors and encoded symbols is established beforehand through experimental calibration. During calibration, several structural colors that can be reliably distinguished by the human eye or image sensor under white light illumination are selected, and each color is assigned a unique symbol. This mapping table should be embedded in the processing software and decoding application as a system configuration file to ensure that the production and verification ends use the same mapping rules.

[0040] In actual encoding, each structural color is sequentially retrieved from the ordered list of structural colors and then matched against a lookup table. The matching process can employ either exact matching or fuzzy matching: for color categories obtained from image analysis, the corresponding coded symbol in the lookup table is directly searched; if slight deviations in lighting or angle cause color recognition to fall between two adjacent categories, a nearest neighbor rule can be introduced. For example, the distance between the hue value of the color to be identified and the hue thresholds of each standard color is calculated, and the category with the smallest distance is taken as the matching result. After matching, the structural color of each encoding unit is replaced with a coded symbol. This symbol list retains the original order information, and each symbol occupies only one character, greatly compressing the data volume.

[0041] S205. According to the arrangement order, the various coding symbols are concatenated in sequence to obtain the coding sequence, which serves as the unique anti-counterfeiting ID of the diamond.

[0042] After obtaining the list of coded symbols corresponding to all coded units, the final step is to concatenate these symbols into a continuous string according to their order of arrangement in the barcode area. No separators, prefixes, or suffixes should be inserted during the concatenation process to ensure the uniqueness and standardization of the string, facilitating subsequent database queries and comparisons. In practice, each character in the symbol list can be appended to an empty string variable. For example, the symbol list [V, B, C, G, Y, O, R, X, V, B, C, G] can be concatenated to obtain the string "VBCGYORXVBCG". This string is the diamond's unique anti-counterfeiting ID, which has the following characteristics: its length is equal to the number of coded units (12 digits in this example) for easy manual recording and system management; the ID string completely corresponds to the physical structural color sequence of the diamond's surface, meaning it can be decoded from the physical identifier and used for reverse verification of the processing correctness.

[0043] Once a unique anti-counterfeiting ID is obtained, it can be associated with the diamond's identity information and encrypted and stored in a database. During distribution and sales, any third party can scan the barcode area using a mobile app, obtain a decoded ID through the same color analysis and symbol conversion process, and compare it with the registered ID in the database to quickly verify the diamond's authenticity. If the decoded ID and registered ID match perfectly, the diamond is considered genuine; otherwise, verification fails.

[0044] In this embodiment, by illuminating each encoded unit with white light and acquiring images, the actual structural color of each unit is obtained. The grating period is then associated with and summarized with the structural color to form a standardized encoding mapping relationship, providing a reliable data foundation for subsequent reverse mapping and decoding verification. Simultaneously, by converting the structural color into a unified encoded symbol and concatenating it sequentially into a string, the conversion from physical structural color sequence to digital anti-counterfeiting ID is achieved, facilitating subsequent storage, transmission, and database comparison.

[0045] The following section provides a detailed explanation of defining barcode regions and dividing coding units. Please refer to [link / reference]. Figure 3 , Figure 3 A flowchart illustrating an embodiment of the method for producing a diamond anti-counterfeiting label provided in this application, comprising defining a barcode area and dividing encoding units, the embodiment including: S301. Delineate a continuous area on the surface of the diamond matrix as a barcode area, and determine the starting and ending boundaries of the barcode area; Before commencing femtosecond laser processing, the specific location and size of the barcode area on the diamond substrate must first be determined. The diamond substrate is typically cut and polished, with clearly defined girdle facets, table facets, and culet facets. Since the girdle facets remain partially exposed after diamond setting, facilitating later scanning and identification, and having minimal impact on the overall aesthetics of the diamond, the barcode area is preferably placed on the girdle facets. In practice, the diamond substrate is fixed on the three-dimensional moving stage of the femtosecond laser processing platform, and the diamond surface is observed using a high-powered microscope. Based on the diamond's size and coding capacity requirements, the shape, length, and width of the barcode area are set in the processing software. The barcode area is typically rectangular, with its length along the circumference of the girdle facets or the tangent to the edge of the table facets, and its width perpendicular to its length. For example, for a 0.5-carat diamond with a girdle width of approximately 0.3mm, the barcode area can be set to a length of 1.2mm and a width of 0.12mm; for a 1-carat diamond with a girdle width of approximately 0.5mm, the length can be set to 2.0mm and the width to 0.2mm.

[0046] When defining the area, both the starting and ending boundaries need to be determined. The starting boundary refers to the beginning position of the barcode area along its length, while the ending boundary refers to the ending position. These two boundaries can be precisely located using the coordinate system of the laser processing platform. For example, the laser focus is moved to a reference point on the girdle surface, which is used as the origin of the coordinate system. Then, a preset distance is moved along the tangent of the girdle to obtain the coordinates of the starting boundary, and then another 1.2 mm is moved to obtain the coordinates of the ending boundary. The direction of the line connecting the starting and ending boundaries is the preset direction, which is the length direction of the barcode area.

[0047] S302. Divide the barcode area along a preset direction from the start boundary to the end boundary to obtain several coding units; After defining the overall area of ​​the barcode region, it needs to be divided along its length into multiple continuous coding units of equal or unequal width. Each coding unit is an independent basic unit for processing and identification, and its width determines the number of coding units and the identification resolution. During segmentation, the number of coding units is first determined, and then the width of each unit is obtained by dividing the total length of the barcode region by the number of units.

[0048] Utilizing the positioning function of the laser processing platform, starting from the initial boundary, a dividing line is marked every unit width along a preset direction. The dividing line can be a virtual logical boundary, or it can be physically distinguished from adjacent coding units by leaving tiny gaps at the boundaries during actual processing. To avoid interference between the grating structures of adjacent coding units, extremely narrow separating bands can be maintained between units without affecting the overall visual continuity. Based on these dividing positions, the barcode area is divided into several consecutive, adjacent coding units, each with an independent spatial coordinate range.

[0049] S303. Assign a sequential index to each coding unit to determine the arrangement order.

[0050] After the physical partitioning of coding units is completed, a unique sequential index needs to be assigned to each coding unit to determine the arrangement order of the structure color sequence. The assignment of sequential indices usually follows a natural ascending order from the start boundary to the end boundary. That is, the coding unit closest to the start boundary is assigned index 1, its next adjacent unit is assigned index 2, and so on, until the unit at the final end boundary is assigned an index.

[0051] The index number is not only used to sequentially set parameters for each unit during processing, but it is also written into the diamond's identity information database and bound to the final anti-counterfeiting ID. Furthermore, to automatically identify the starting direction during actual imaging and prevent incorrect decoding order due to reversed diamond placement, asymmetrical visual features can be set at both ends of the barcode area. For example, an additional large calibration mark can be processed near the starting boundary, while no mark or a different mark can be used at the ending boundary. In this way, the image processing algorithm can automatically determine the starting end by detecting the position of the calibration mark, thereby ensuring that the combination order of structural colors during decoding is consistent with the index order.

[0052] In this embodiment, by defining a continuous and flat barcode area on the edge of the diamond's girdle or table, and dividing it into several coding units at equal intervals along a preset direction, the starting boundary and the ending boundary are determined. Asymmetric calibration marks are set at both ends, which not only ensures that the sequential index of each unit is accurate during processing, but also facilitates the direction recognition and starting end positioning in the decoding image processing, effectively preventing decoding sequence errors caused by the diamond being placed in the wrong direction.

[0053] Based on the unique anti-counterfeiting ID, determine the structural color corresponding to each coding unit, and then determine the grating period corresponding to each coding unit. Please refer to [link / reference]. Figure 4 , Figure 4 This is a flowchart illustrating an embodiment of the method for producing a diamond anti-counterfeiting label provided in this application, in which the grating period is determined based on a unique anti-counterfeiting ID. This embodiment includes: S401. Parse the unique anti-counterfeiting ID and extract the structural color corresponding to each coding unit according to the arrangement order of each coding unit. After obtaining the diamond's unique anti-counterfeiting ID, the string needs to be parsed into a sequence of structural colors corresponding one-to-one with the coded units. The unique anti-counterfeiting ID is a string composed of coded symbols, where each character corresponds to the structural color of a coded unit, and the order of the characters matches the spatial arrangement of the coded units within the barcode area. During parsing, first confirm the length of the anti-counterfeiting ID, which should equal the total number of coded units contained in the barcode area. For example, the string "VBCGYORXVBCG" has a length of 12, indicating that the diamond's barcode area contains 12 coded units. Then, read each character in the string sequentially from left to right. During reading, the first character corresponds to the coded unit with index 1, the second character to the coded unit with index 2, and so on, until the last character corresponds to its index.

[0054] For each character read, it needs to be converted into its corresponding structural color name. This conversion process relies on a pre-established lookup table between encoded symbols and structural colors. To ensure the accuracy of parsing, format validation should be performed during the parsing process. If the string contains illegal characters not defined in the lookup table, the anti-counterfeiting ID is deemed invalid, and an error message is displayed. After parsing, a list of structural colors is output, where each element is the structural color name of the corresponding encoded unit.

[0055] S402. Based on the encoding mapping relationship, query the raster period interval corresponding to each structural color; After obtaining the structural color of each coding unit, it is necessary to reverse-look up the grating period interval corresponding to each structural color based on the established coding mapping relationship. The coding mapping relationship is usually recorded in the form of period interval-color, for example: 150nm~200nm corresponds to violet, 200nm~260nm corresponds to blue, 260nm~320nm corresponds to cyan, and so on.

[0056] For each color in the structural color list, a matching query is performed in the mapping table. The color name is used as the key to find its corresponding period range. If the mapping table uses period ranges instead of single period values, each structural color corresponds to a continuous range of values. This range characterizes the allowable fluctuation space of the grating period that can produce that structural color. Due to the inherent error in femtosecond laser processing, as long as the actual processed grating period falls within this range, the display of the structural color is within an acceptable range. After the query is completed, each encoding unit obtains a corresponding period range, and this range information is used to select the specific processing target value.

[0057] S403. Select a target period value within each grating period interval as the grating period corresponding to the coding unit.

[0058] After obtaining the period interval for each coding unit, a specific target period value needs to be selected from each interval. This target period value will serve as the basis for parameter setting during femtosecond laser processing or as a benchmark for comparison with the measured period.

[0059] There are several methods for selecting the target period value. One method is to take the median of the period range. For example, for the purple range of 150nm to 200nm, the median is 175nm. Another method is to select a specific characteristic value within the range based on practical processing experience. For instance, experimental calibration revealed that when the pulse energy density is 0.8J / cm² and the scanning speed is 5mm / s, the measured grating period stabilizes around 180nm, and the purple saturation is highest at this period. Therefore, the target period value for the purple range can be set to 180nm instead of the median of 175nm. This method effectively optimizes the display effect of structural colors.

[0060] Once the target period value is selected, each coding unit obtains a unique grating period value. These target period values ​​are stored in the laser processing task file and used to control the pulse energy density and scanning speed of the femtosecond laser, so that the actual grating period processed by each coding unit is as close as possible to the target value.

[0061] In this embodiment, by parsing the anti-counterfeiting ID in string form into a structural color sequence and using the established encoding mapping relationship to look up the grating period interval corresponding to each structural color, a specific target period value is selected, thus realizing the reverse mapping from digital ID to physical processing parameters. This process can be used for parameter preset before laser processing to ensure that the processed grating period is consistent with the ID, and it can also be used for verification after processing. By comparing the theoretical target period with the actual measured period, unqualified encoding units can be quickly identified and reprocessing or scrapping can be triggered, thereby ensuring the quality of each diamond anti-counterfeiting mark and the uniqueness of the ID.

[0062] This application also provides an embodiment of a method for decoding diamond anti-counterfeiting marks. Please refer to [link / reference]. Figure 5 , Figure 5 This is a flowchart illustrating an embodiment of the decoding method for diamond anti-counterfeiting marks provided in this application. The embodiment includes: S501. Obtain the pre-established encoding mapping relationship, which is used to associate the grating period with the structure color; Before the decoding process begins, it is necessary to first obtain the encoding mapping relationship established during the diamond anti-counterfeiting label production process. This encoding mapping relationship is the bridge connecting the raster period and the structural color, and it is also the key basis for restoring the image color to the anti-counterfeiting ID.

[0063] The encoding mapping relationship is typically stored as a configuration file in a cloud server, blockchain system, or local database of a mobile application. This relationship table records the correspondence between different raster period intervals and structural colors; for example, a short period corresponds to purple, a longer period to blue, an even longer period to cyan, and so on. To ensure the accuracy and security of decoding, the encoding mapping relationship should be completely consistent with the mapping relationship used when creating the diamond anti-counterfeiting label. If the mapping relationship changes, the decoding result will not match the registered ID. Therefore, all production and decoding ends in the entire anti-counterfeiting system should use the same version of the mapping relationship table.

[0064] S502. Acquire images of the barcode area using white light illumination, and locate and segment the images to obtain the image areas corresponding to each coding unit; After obtaining the encoding mapping relationship, the barcode area on the diamond needs to be imaged. Place the diamond on a stable surface, ensuring the barcode area faces the camera. Use the phone's rear camera in macro mode, and simultaneously turn on the phone's flash as a white light source. The white light emitted by the phone's flash illuminates the barcode area at a certain angle, and the camera captures the image at the corresponding viewing angle. To improve the success rate of the shot, the distance between the phone and the diamond can be adjusted appropriately until the barcode area is clearly visible on the screen.

[0065] The acquired color image contains the entire barcode area and part of the surrounding background. For subsequent processing, the image needs to be localized and segmented. Localization aims to find the position and orientation of the barcode area within the entire image. Since the barcode area is typically located on the girdle or table edge of a diamond, its shape is a long, narrow rectangle, and it may have asymmetrical calibration marks at both ends. Methods such as edge detection, morphological analysis, or template matching are used to quickly locate the starting and ending boundaries of the barcode area. After localization, segmentation is performed, which involves independently separating each coding unit within the barcode area from the overall image. Since the coding units are arranged adjacently according to a preset width, the theoretical boundary of each coding unit can be calculated based on the length direction of the barcode area, the total length, and the number of coding units. Within each boundary range, the corresponding pixel area is extracted as an image region for one coding unit.

[0066] S503. Perform color analysis on the image region corresponding to each coding unit, and determine the structural color of each coding unit according to the coding mapping relationship; After obtaining the image region of each coding unit, color analysis is required for each region to determine the structural color category it presents. Specifically, for each coding unit's image region, the average red, green, and blue values ​​of all pixels within that region are first calculated. Since a single coding unit is very small, typically occupying a certain number of pixels in a mobile phone macro image, the calculated average value can represent the overall color of that unit. The red, green, and blue average values ​​are then converted into a hue, saturation, and brightness color space, and the hue value is extracted as the primary basis for color determination. The hue value is an angular value; different angular ranges correspond to different color categories. For example, a certain angular range corresponds to red, adjacent ranges correspond to orange, and so on.

[0067] To match the color categories in the encoding mapping, the hue threshold ranges corresponding to each color category need to be pre-calibrated. This calibration is accomplished experimentally: under fixed illumination and viewing angle conditions, the hue value range of grating structure samples with known periods is measured. After calculating the hue value of a coding unit, it is compared with the threshold ranges of each color category, and the color corresponding to the range that falls into is taken as the structural color of that unit. If the hue value of a coding unit happens to fall near the boundary between two color ranges, a tolerance mechanism can be introduced, such as selecting the nearest color category, or taking a second picture of the unit to obtain a more stable color value. Finally, each coding unit outputs a specific structural color name.

[0068] S504. According to the arrangement order of each coding unit, the structural colors of each coding unit are combined into a sequence in sequence, and the sequence is used as the decoded anti-counterfeiting ID.

[0069] After obtaining the structural colors of all coded units, these colors need to be combined into a sequence according to the spatial arrangement of the coded units in the barcode area. This order should strictly match the sequence index assigned during production to ensure that the decoded anti-counterfeiting ID and registration ID can be correctly compared.

[0070] During the combination process, the order needs to be determined. Since the image localization has identified the start and end boundaries, it is clear which coding unit is the first and which is the last. Following the order from the start boundary to the end boundary, the structural color name of each coding unit is extracted sequentially. These structural color names are then converted into corresponding coding symbols. The conversion is based on the obtained coding mapping relationship; for example, purple corresponds to the letter V, blue to the letter B, cyan to C, green to G, yellow to Y, orange to O, red to R, and dark red to X. Each structural color is replaced with a coding symbol.

[0071] All encoded symbols are concatenated sequentially into a continuous string, which is the decoded anti-counterfeiting ID. After decoding, the mobile application can send the anti-counterfeiting ID to the database for comparison. If the ID exists in the registration database and matches the diamond's identity information, "Verification passed" and detailed diamond information are returned; if the ID does not exist or does not match, "Verification failed" is displayed.

[0072] In this embodiment, images of the barcode area are captured using portable devices such as mobile phones. Color analysis and symbol conversion are then performed based on pre-acquired encoding mapping relationships to ultimately decode the anti-counterfeiting ID, which is then compared with a database to verify authenticity. No professional equipment is required; ordinary consumers can quickly complete the verification at the point of purchase using only their mobile phone flashlight and a dedicated app, significantly lowering the barrier to entry for anti-counterfeiting technology. Simultaneously, the decoding process automatically completes image positioning, segmentation, color analysis, and stitching, eliminating subjective errors from human judgment. Verification results are returned instantly, significantly improving user experience and anti-counterfeiting efficiency.

[0073] This application also provides an embodiment of a diamond anti-counterfeiting label; please refer to [link / reference]. Figure 6 , Figure 6 This is a schematic diagram of the structure of one embodiment of the diamond anti-counterfeiting label provided in this application. The diamond anti-counterfeiting label is manufactured using the aforementioned method. Specifically, the diamond anti-counterfeiting label includes a diamond substrate 601 and a barcode area 602 formed on the surface of the diamond substrate 601. The barcode area 602 is pre-divided into several coding units. These coding units are arranged adjacent to each other along a preset direction, and each coding unit has an independent spatial position and sequential index. The division method can be equal-width segmentation, and the width of the coding unit is set according to the femtosecond laser processing and the recognition resolution of the mobile phone camera. For example, the barcode area 602 is generally a long, narrow rectangle, and its length and width are determined according to the diamond size. The number of coding units determines the number of digits in the anti-counterfeiting ID.

[0074] Each coding unit contains a grating structure with a different period. These grating structures are formed using femtosecond laser processing. Due to variations in the pulse energy density or scanning speed of the femtosecond laser, the grating periods within different coding units differ from one another. When white light shines on the barcode area 602 at a certain angle, the grating structures with different periods diffract the white light, causing each coding unit to exhibit a different structural color. The type of structural color depends on the specific value of the grating period, and a fixed structural color corresponds to the same period interval.

[0075] The structural colors presented by all coded units, arranged in a preset order within barcode area 602, constitute the diamond's unique anti-counterfeiting ID. This ID is typically represented by a sequence of coded symbols; for example, each structural color maps to a letter or number, concatenated sequentially to form a string. This ID is associated with the diamond's identity information and is encrypted and stored in a database for comparison during subsequent verification. Because the grating structure is a permanent physical structure on the surface of the diamond matrix 601, it cannot be copied or removed by chemical etching, mechanical polishing, or printing, thus providing a high level of anti-counterfeiting security. Furthermore, consumers can simply use their mobile phone flashlight to illuminate and photograph the barcode area 602 at the point of purchase, and quickly decode and verify its authenticity via a dedicated app, without requiring any professional equipment.

Claims

1. A method for manufacturing a diamond anti-counterfeiting label, characterized in that, The manufacturing method includes: A barcode area is defined on the surface of a diamond matrix, and the barcode area is divided into several coding units along a preset direction; By controlling a femtosecond laser, grating structures with different grating periods are fabricated on each of the coding units; wherein, different grating structures correspond to different structural colors; Establish the encoding mapping relationship between the grating structure and the structural color of each encoding unit, and use the structural color sequence of all encoding units as a unique anti-counterfeiting ID; Based on the unique anti-counterfeiting ID, the structural color corresponding to each of the coding units is determined, and then the grating period corresponding to each of the coding units is determined by combining the coding mapping relationship.

2. The manufacturing method according to claim 1, characterized in that, The step of establishing the encoding mapping relationship between the grating structure and the structural color of each encoding unit, and using the structural color sequence of all encoding units as a unique anti-counterfeiting ID, includes: Each of the coding units is illuminated with white light and an image is acquired to obtain the structural color presented by each of the coding units; The grating period of each coding unit is summed with the structural color to obtain the coding mapping relationship; Based on the arrangement order of each coding unit in the barcode area, the structural colors of each coding unit are combined sequentially to form a structural color sequence, and the structural color sequence is used as a unique anti-counterfeiting ID.

3. The manufacturing method according to claim 2, characterized in that, The step of sequentially combining the structural colors of each coding unit according to their arrangement order in the barcode area to form a structural color sequence, and using this structural color sequence as a unique anti-counterfeiting ID, includes: The arrangement order of the structural colors is determined based on the position number of each coding unit in the barcode area; The structural color of each coding unit is converted into a corresponding coding symbol, and there is a one-to-one correspondence between the coding symbol and the structural color. According to the arrangement order, the coded symbols are sequentially concatenated to obtain a coded sequence, which serves as the unique anti-counterfeiting ID of the diamond.

4. The manufacturing method according to claim 1, characterized in that, The step of defining a barcode area on the surface of a diamond matrix and dividing the barcode area into several coding units along a predetermined direction includes: A continuous area is delineated on the surface of the diamond matrix as a barcode area, and the start and end boundaries of the barcode area are determined. The barcode area is divided along a preset direction from the starting boundary to the ending boundary to obtain several encoding units; Each of the coding units is assigned a sequential index to determine the arrangement order.

5. The manufacturing method according to claim 1, characterized in that, The process involves controlling a femtosecond laser to fabricate grating structures with different grating periods on each of the coding units, wherein different grating structures correspond to different structural colors, including: Each coding unit is scanned according to preset laser parameters. Different target grating periods are set for different coding units by changing the pulse energy or scanning speed. A grating structure with a corresponding period is formed in each coding unit along the preset scanning path, so that different coding units obtain different structural colors.

6. The manufacturing method according to claim 1, characterized in that, The step of determining the structural color corresponding to each encoding unit based on the unique anti-counterfeiting ID, and then determining the grating period corresponding to each encoding unit, includes: The unique anti-counterfeiting ID is parsed, and the structural color corresponding to each encoding unit is extracted according to the arrangement order of each encoding unit; Based on the encoding mapping relationship, query the grating period interval corresponding to each structural color; A target period value is selected within each grating period interval and used as the grating period corresponding to that coding unit.

7. The manufacturing method according to any one of claims 1 to 6, characterized in that, The manufacturing method further includes: after processing, performing optical detection on the structural color of each coding unit, and comparing the detected structural color with the structural color expected according to the coding mapping relationship; if the comparison result is inconsistent, the coding unit is reprocessed.

8. A method for decoding diamond anti-counterfeiting labels, characterized in that, The decoding method includes: Obtain a pre-established encoding mapping relationship, which is used to associate the grating period with the structure color; Images of the barcode area are acquired by white light illumination, and the images are located and segmented to obtain the image areas corresponding to each coding unit; Color analysis is performed on the image regions corresponding to each coding unit, and the structural color of each coding unit is determined according to the coding mapping relationship. According to the arrangement order of each of the coding units, the structural colors of each coding unit are sequentially combined into a sequence, and the sequence is used as the decoded anti-counterfeiting ID.

9. A diamond anti-counterfeiting label, characterized in that, It is prepared by the manufacturing method according to any one of claims 1 to 7.

10. The diamond anti-counterfeiting label according to claim 9, characterized in that, This includes the diamond matrix and the barcode area formed on its surface; The barcode area is divided into several coding units, each of which has a grating structure with a different period, so that each coding unit presents a different structural color under white light. The structural color sequence of all the encoded units is arranged in a preset order as the unique anti-counterfeiting ID of the diamond.

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