A method for producing perfectly spherical, nucleated, round cultured pearls using abalone oysters.

Abstract

Due to its different body structure from bivalves and the influence of pressure from the movement of its powerful leg muscles, it is now possible to produce perfectly spherical, nucleated, and perfectly round cultured pearls using abalone as the mother oyster, which was previously considered impossible. [Solution] In pearl cultivation using abalone as the mother oyster, the nucleus insertion site is designated as the anterior lobe of the mantle where the nucleus is stably held, and the nucleus to be inserted is of a size that can accommodate this site, and can be stably held without detaching, thereby making it possible to produce spherical, nucleated, perfectly round pearls that could not be produced before. Furthermore, by using a method of cultivation with multiple nucleus insertions, it is possible to produce perfectly spherical, nucleated, perfectly round pearls with excellent sphericity and smoothness from the second time onward. Moreover, in this method of repeating nucleus insertion and cultivation multiple times, it is also possible to produce hemispherical pearls from the same abalone oyster in parallel.

Description

Technical Field

[0001] A method for obtaining cultured pearls from Akoya oysters was developed in Japan over 100 years ago. Since then, it has continued to develop, and currently, the types of pearl oysters are not limited to Akoya oysters but have expanded to include white-lipped oysters that inhabit overseas, etc. Also, not only seawater cultured pearls but also freshwater pearls using oysters that inhabit freshwater are produced and widely supplied to the world's jewelry market. Currently, the producing countries of cultured pearls include not only Japan but also Australia, the Philippines, Indonesia, Myanmar, Tahiti, Vietnam, and China overseas.

[0002] The basic principle of the method for manufacturing nucleated round cultured pearls of bivalves such as Akoya oysters and white-lipped oysters is to insert a nucleus processed into a spherical shape from the shell of a freshwater bivalve into the gonad in its body, and then attach epithelial cells of the mantle (piece), which is a section cut from the mantle of the same species of oyster, to this nucleus, and then culture it. During this culturing period, the epithelial cells of the mantle, which are pieces attached to the inserted nucleus, divide and proliferate, and by wrapping the entire inserted nucleus, a pearl sac (pearl sack) is formed. Furthermore, the inner surface of this pearl sac secretes nacre, and the entire surface of the nucleus is covered with nacre, thereby forming a pearl. The above is the basis of the method for manufacturing nucleated round pearls established with Akoya oysters, which are bivalves, and has been extended and applied to pearl culture of other bivalves.

[0003] The inner surface of the shell of the abalone oyster, which is a univalve, has metallic characteristic colors such as green and blue different from those of Akoya oysters, and moreover, has an attractive luster with a changing color tone depending on the viewing angle. Now, let's touch on abalone pearls (avalon pearls, Abalone Pearls). Occasionally, unusually shaped natural abalone pearls are found inside abalone shells. Natural abalone pearls are extremely rare and precious pearls that are created by chance. These baroque pearls from abalone shells, possessing a beautiful luster, are not spherical, but due to their rarity and unique shape, they are often decorated with precious metals and made into very expensive jewelry. Furthermore, no reports have been found of perfectly spherical pearls being found among these natural abalone pearls.

[0004] For this reason, several attempts have been made to produce perfectly round pearls similar to those of Akoya oysters using abalone oysters. However, to date, the only pearls sold commercially under the name "Abalone Pearl" are not spherical, but rather deformed baroque pearls and hemispherical pearls. In other words, the cultivation technology for perfectly spherical, nucleated, round pearls has not yet been established, and therefore, they are not available on the market. In the pearl cultivation industry, spherical pearls are called round pearls, and hemispherical pearls are called semi-circular pearls. In this invention, the term "semi-circular pearl" refers to a semi-circular pearl that has a hemispherical surface rather than a semicircular shape. This invention provides a cultivation technology that enables the production of perfectly spherical, nucleated, round pearls from abalone shells, a type of pearl that has not been successfully produced until now.

[0005] Now, let's touch upon the definition of a nucleated, perfectly round pearl. Non-patent document 2, "Pearl Guidelines 2020," on page 19, describes a perfectly round pearl as "a pearl whose entire surface is covered with nacre." In other words, a perfectly round pearl does not necessarily mean that its shape is perfectly spherical. Therefore, in this invention, in order to emphasize that its shape is perfectly spherical, we deliberately use the expression "perfectly spherical nucleated perfectly round pearl." Furthermore, page 74 states that "the material of the nucleus used in nucleated pearl cultivation is limited to the nacreous layer of freshwater bivalve shells, and no other materials are permitted." The reason for this is also explained. The present invention's "method for obtaining a perfectly spherical, nucleated, perfectly round pearl" does not limit the material of the nucleus in any way; however, from the viewpoint of the strength and quality of the resulting pearl, it is naturally recommended to use a nucleus obtained from a freshwater bivalve in accordance with pearl guidelines. [Background technology]

[0006] First, pearl cultivation involves inserting a nucleus into the body of a pearl oyster and allowing nacreous tissue to form on its surface (this is referred to in the industry as "making the pearl grow"). However, simply inserting a nucleus into the pearl oyster is not enough to "make the pearl grow." It is necessary to attach a section (piece) of mantle epithelial cells, taken from a similar species of oyster that has the function of secreting nacreous tissue, to the surface of the inserted nucleus. During the cultivation period, this piece grows to cover the surface of the nucleus, forming a sac-like structure that encloses the nucleus, thus creating a pearl sac. Furthermore, nacre is secreted on the inner surface of this pearl sac, so that the entire surface of the nucleus is covered with nacre, and a perfectly round pearl is formed. Therefore, the insertion of the nucleus, the adhesion of the piece, the stable maintenance of the adhesion between the inserted nucleus and the piece, and cultivation are essential conditions for pearl formation.

[0007] Bivalve mollusks such as pearl oysters and white-lipped oysters feed on plankton floating in the water, which they take in and consume from the seawater. Therefore, they do not need to move around for the purpose of hunting. Generally, pearl oysters are cultivated by placing oysters with inserted nuclei into cultivation cages and suspending them in seawater for a predetermined period of time. During this time, a pearl sac forms inside the oyster's body, and then the nacreous layer forms on the inside (the surface of the inserted nucleus). In contrast, snails such as abalone and turban shells feed on seaweed such as wakame and kelp, and to catch these, the snails need to actively move around in search of food. Also, when abalone senses danger, they will firmly cling to rocks or other surfaces to protect themselves. For this reason, abalone have well-developed foot muscles, and the fact that they move around by crawling using these foot muscles is a major difference from bivalves.

[0008] When attempting to apply the nucleus insertion procedure used for pearl oysters to abalone oysters, the vigorous movement of the leg muscles significantly hinders the procedure. Therefore, anesthesia is necessary to suppress this movement of the leg muscles. Anesthetics include drugs such as benzocaine, clove oil, phenoxyethanol, and phenoxypropanol, as well as CO2 gas. However, an aqueous solution of magnesium chloride (nigari), a component of seawater, also has an anesthetic effect. Moreover, magnesium chloride is harmless. In the examples described later, this aqueous solution of magnesium chloride is used as an anesthetic.

[0009] Now, while this anesthesia method makes the nucleation procedure itself significantly easier, there is another challenge that needs to be overcome. In pearl cultivation of bivalves such as Akoya oysters, the gonads are used as the site from which a nucleus is inserted to obtain a pearl. In the internal structure of bivalves such as Akoya oysters, the gonads are located away from the liver and internal organs, and are organs with a large space. Therefore, nucleus insertion procedures can be performed relatively easily without damaging the liver or internal organs, and it is also easy to insert large nuclei, making it possible to produce large pearls.

[0010] In contrast, the internal structure of abalone is quite different from that of pearl oysters. The gonads are closely located to the internal organs (such as the liver), making it technically extremely difficult to insert a nucleus into the gonads without damaging the internal organs. In oysters that overcome this difficulty and can be successfully implanted with a nucleus, and whose cultivation can be continued without subsequent nucleus removal, a pearl sac forms within the gonad. However, this pearl sac itself is subjected to compression by the foot muscles, forcing it to deform. As a result, the shape of the pearl formed within this deformed pearl sac is a deformed pearl, even though a perfectly spherical nucleus was inserted, resulting in a baroque pearl.

[0011] Under these circumstances, in Japan, various measures have been taken to prevent the inserted nucleus from being dislodged by the movement and pressure of the leg muscles, as described in Patent Documents 1-3. These measures include drilling holes in the shell or using wire or fishing line to fix the nucleus in place. These measures aim to prevent the dislodged nucleus and suppress its movement within the shell. However, even when pearl cultivation is successful using these methods, the resulting pearls are deformed baroque pearls. Patent Document 3 describes a method for obtaining hemimorphic pearls. Patent Document 4 was published, but no request for examination was filed, and it was deemed withdrawn. According to this published patent information, a perfect sphere can be obtained, but there is a description of "the trace of thread used to prevent the piece and nucleus from separating." In other words, a perfectly spherical, nucleated, perfectly round pearl without deformation or damage has not been obtained to date. Patent Document 5 states that during nucleus insertion, the gonad atrophies, creating a gap between it and the mantle, and that the nucleus is inserted into this gap. However, the pearls obtained are still considered baroque pearls. Patent document 6 describes a pearl cultivation method in Chile, in which the nucleus insertion site is designated as the gonad, and the incised area is sutured with absorbable sutures to prevent nucleus removal and improve yield. However, even in this case, despite inserting a perfectly spherical nucleus, the resulting pearls are described as baroque pearls.

[0012] Furthermore, Non-Patent Document 3 describes a method in which a flat disc with one side spherical is pressed between the mantle and the shell using a special tool, and after cultivating it for about 1.5 to 2.5 years, the pearl portion is cut out from the shell to obtain a semi-form pearl. Currently, this technology is used to produce hemispherical abalone culture pearls, which are then processed into pendants and earrings and sold under the brand name Arapawa Pearls. https: / / arapawabluepearls.co.nz

[0013] In other words, although various technologies have been developed to obtain nucleated, perfectly round pearls from abalone oysters, the pearls that have been successfully obtained are all baroque pearls, hemispherical pearls, or pearls with flaws. A technology has not yet been established to obtain perfectly round, nucleated pearls that are flawless and have excellent sphericity and smoothness. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Japanese Patent Publication No. 1974-107888 describes a method for cultivating pearls using abalone as the mother oyster, by making a hole of an appropriate size in the upper part of the gonad on the dorsal side of the mother oyster, and fixing a nucleus to be inserted into the oyster body using wire or the like. [Patent Document 2] Japanese Patent Publication No. 1981-154936 describes a method in which a nucleus and pieces are inserted into the inside of the abalone's mantle so that they are in contact with each other, the abalone is then placed in a cylinder, and the abalone is cultivated in seawater to form a pearl. [Patent Document 3] Japanese Patent Publication No. 2018-110553 describes a method for forming a semi-form pearl by inserting a nucleus between the shell and the mantle from the head side of the abalone using a straw-shaped tube. [Patent Document 4] Japanese Patent Publication No. 1986-15636 describes a method for forming a pearl by drilling a hole in the mantle of an abalone at the attachment point where it adheres to the shell edge, drilling through holes in the nucleus and piece to prevent them from separating, passing nylon fishing line through these holes, and then fixing the nucleus and piece from the outside by passing the nylon fishing line through a hole drilled in the shell. However, this patent has been deemed withdrawn, and no reports of actually obtaining a perfectly spherical pearl using this method have been found since. [Patent Document 5] Patent No. 7418626 (2024) describes a method for inserting a nucleus into abalone oysters. While the insertion site is the gonad, inserting the nucleus into this gonad is extremely difficult. Therefore, the method involves inserting the nucleus into the gap between the mantle and the gonad that forms after sperm or oviposition, as these processes contract. However, the resulting pearl is not perfectly spherical, but rather a deformed baroque shape. [Patent Document 6] International Patent Application WO2016183695 is a method for obtaining pearls from abalone shells developed in Chile. The nucleus is inserted after making an incision in the abalone's gonad, but in this case, due to the movement of the adductor muscles, the inserted nucleus is likely to be dislodged. Therefore, a method of preventing the nucleus from being dislodged is to sew up this incision with absorbent sutures. However, even in this case, the obtained pearls are deformed baroque pearls. Incidentally, the pearls produced by this technology are sold under the brand name (Atacama Pearls). https: / / atacamapearls.com /

Non-Patent Documents

[0015]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0016] The problem that this invention aims to solve is the development of a technology to produce "perfectly spherical, nucleated, round pearls" with high commercial value, which have been desired but have not been successfully developed until now, using abalone as the mother-of-pearl and possessing rich colors such as unique green and blue not found in other pearl oysters, and also having excellent sphericity and smoothness. [Means for solving the problem]

[0017] This invention was made to solve the aforementioned problems. First, to suppress the vigorous leg muscle movements of the abalone during the procedure, we adopted the anesthetic method used in abalone pearl cultivation. As mentioned earlier, various anesthetic agents have been proposed and all are acceptable, but in this example, we adopted the magnesium chloride aqueous solution method. This anesthetic method suppresses leg muscle movements and facilitates the nucleus insertion procedure.

[0018] In this invention, the insertion site is a part of the mantle tissue, but it is the anterior lobe of the mantle (number 1 in Figures 1 and 2), which has never been given any attention before. This area is a narrow region between the respiratory pore (number 5 in Figures 1 and 2) and the edge of the shell. As shown in Figure 2, the mantle, which is normally spread flat, bends in the direction of the shell (downward in Figure 2) to form the respiratory pore.

[0019] The reason this part of the abalone shell has not been considered as a site for nucleus insertion until now is likely because this region is extremely narrow. In other words, in this anterior lobe, the size of the nucleus that is unlikely to denucleate even under pressure from the foot muscles is only about 3 mm in the case of an abalone with a shell length of 70-80 mm.

[0020] If the size of the nucleus to be inserted is 3 mm, even if a perfectly spherical pearl is obtained by inserting this nucleus, if its size is small, its commercial value will be low. In other words, even if pearls were cultivated using this particular area as the nucleus insertion site, if the resulting pearls had low commercial value, there would be no economic benefit in using this site for cultivation. This is likely one of the reasons why nucleus insertion in this area has not been performed until now.

[0021] However, the anterior lobe has an elongated shape as shown in Figure 2, and this part of the shell is slightly concave along the edge of the shell, making it easier to stably hold smaller-than-usual nuclei that can be housed here. In other words, by using a nucleus that can be accommodated in the anterior lobe, it is less susceptible to compression by the foot muscles, and nucleus denucleation becomes less likely. This means that although the resulting pearls will be smaller, the "yield" will be improved.

[0022] When cultivating and producing pearls, it's desirable to insert the largest possible nucleus, but this defeats the purpose if the nucleus is removed. Similarly, even if small pearls are obtained, they are pointless if they have low commercial value. Furthermore, while this small nucleus is inserted and a pearl is allowed to grow around it, it takes approximately one month for the pearl sac to form from the piece after insertion. During this time, the piece is constantly subjected to pressure from the movement of its leg muscles, which causes deformation and wrinkles in the forming pearl sac. Consequently, the surface of the pearl formed within the pearl sac also exhibits deformation and wrinkles that reflect these effects. Therefore, even if the resulting pearl is perfectly spherical, traces of these wrinkles may remain on its surface. In other words, pearls obtained from the first nucleation are not only smaller in size, but also of considerably lower quality in terms of sphericity and smoothness.

[0023] Spherical pearls are produced, but their value is low. This is a dilemma. This invention resolves this dilemma by repeating the process of nucleus insertion, cultivation, and harvesting (pearl collection) multiple times, as described below. In other words, this method provides a way to produce (cultivate) perfectly spherical abalone pearls with high commercial value, whereas until now, only deformed baroque pearls or hemiformed pearls have been obtained in abalone pearl cultivation.

[0024] In the case of abalone, since it is a single shell, the nucleus can be inserted without splitting the shell, and the pearls can also be harvested without splitting the shell when the abalone are brought ashore. Therefore, after the first cultivation and harvesting, the pearl sac can be carefully cut open to remove the pearl, and then a nucleus can be reinserted into the empty pearl sac, allowing for further cultivation and the production of pearls. Incidentally, in subsequent nuclei insertions, the pearl sac has already formed, so gluing the pieces together is unnecessary.

[0025] After the nucleus is inserted into the pearl sac, the sac attempts to tightly adhere to the inserted nucleus without any gaps. As a result, any deformation or wrinkles that occurred during the first pearl sac formation are naturally corrected, allowing for the formation of pearls with superior sphericity and smoothness. Furthermore, when inserting a nucleus slightly larger than the extracted pearl, a moderate tension is applied to the pearl sac immediately after insertion. This corrects any wrinkles or sagging in the pearl sac, resulting in a larger, perfectly spherical, nucleated, round pearl with superior sphericity and smoothness compared to the previous attempt. Therefore, when using nuclei for subsequent nuclei insertions, it is preferable to use nuclei that are the same size as, or slightly larger than, the pearl extracted the previous time, as the size of the anterior lobe has also increased due to the growth of the oyster. Furthermore, even when inserting a nucleus of the same size as the previously extracted pearl, the nacreous layer will form within the pearl sac, resulting in a larger pearl size by the thickness of the formed nacreous layer. In other words, in a method that involves repeating the process of nucleus insertion, cultivation, and harvesting multiple times, the size of the pearls obtained from the second time onward will increase with each subsequent cycle of nucleus insertion and cultivation. Moreover, the resulting pearls will have superior sphericity and smoothness, making them of high commercial value.

[0026] However, pearls obtained in the first cultivation attempt, while perfectly spherical, are small in size and lack sphericity and smoothness, resulting in low commercial value. Therefore, in this invention, the primary objective of the first pearl cultivation of abalone oysters is not to obtain pearls of high commercial value, but rather to form pearl sacs for use in subsequent cultivations, with the aim of obtaining pearls of high commercial value in the second and subsequent cultivations. Of course, it is possible to select pearls from those collected in the first batch that have relatively good sphericity, or those with unique shapes that are considered to have high commercial value, and commercialize them.

[0027] One might be concerned about whether inserting a larger nucleus in subsequent attempts will result in nucleus denucleation. However, the anterior lobe of the shell has already grown to accommodate a larger nucleus than the previous one. Furthermore, unlike the first time, the already formed pearl sac has integrated into the anterior lobe tissue, allowing the inserted nucleus to be held more firmly by the entire anterior lobe. In fact, the success rate for subsequent attempts is extremely high, exceeding 90%, although this naturally depends on the skill of the nucleus insertion procedure.

[0028] Naturally, this method of repeatedly inserting nuclei, cultivating, and harvesting is not limited to the second time; pearl cultivation can be continued for a third, fourth time, and so on. In this case, as mentioned earlier, each subsequent attempt will yield pearls that are larger in size than those obtained in the previous attempt. This is also a major feature of the present invention. First, a major feature of this invention is that the nucleus insertion site is the anterior lobe. Furthermore, although the nucleus insertion, cultivation, and harvesting are repeated multiple times, a pearl sac is formed during the first cultivation, and in subsequent cultivations, this pearl sac is used to obtain perfectly spherical, nucleated, round pearls. The features of the method of this invention are summarized in Table 1. [Table 1]

[0029] In the cultivation period for obtaining perfectly spherical pearls according to this invention, the process of inserting a nucleus, cultivating, and harvesting is repeated multiple times every six months to one year. However, by inserting a nucleus into the anterior lobe and inserting a flattened hemispherical nucleus between the mantle and the shell in parallel, it becomes possible to obtain multiple perfectly spherical, nucleated, round pearls during the cultivation period, and then finally extract a hemispherical pearl from the shell. In other words, it is possible to produce both perfectly spherical, nucleated, round pearls and hemispherical pearls simultaneously. [Effects of the Invention]

[0030] 1. By using the anterior lobe of the mantle instead of the gonad, as is done with Akoya oysters, as the nucleus insertion site, and by ensuring that the size of the inserted nucleus is large enough to be contained within this anterior lobe, making it difficult for the nucleus to detach and allowing for stable retention, a pearl sac is formed that produces pearls with superior sphericity and smoothness in subsequent insertions. By removing the pearl from this pearl sac and inserting a new nucleus into the now-empty pearl sac, it becomes possible to obtain "nucleated, perfectly round abalone pearls with superior sphericity and smoothness" comparable to Akoya pearls, which was previously unattainable. 2. By using a nucleus of the same or slightly larger size as the previous one for subsequent nuclei insertions, it becomes possible to obtain larger, more perfectly round, nucleated pearls with superior sphericity and smoothness with each repeated nucleus insertion and cultivation. 3. Depending on the skill level of the nucleus insertion procedure, the rate of nucleus removal is low in the second and subsequent insertions and cultivation, making it possible to obtain perfectly round, nucleated pearls with excellent sphericity and smoothness at a high yield of at least 90%. 4. By simultaneously inserting a nucleus into the anterior lobe and inserting a flattened hemispherical nucleus between the mantle and the shell, it is possible to obtain multiple perfectly spherical, nucleated, round pearls during the cultivation period. Furthermore, by finally removing the hemispherical pearls that have grown attached to the shell, it is possible to harvest multiple perfectly spherical, nucleated, round pearls during this cultivation period and obtain hemispherical pearls at the end. In other words, it is possible to produce both perfectly round and hemispherical pearls simultaneously. 5. Furthermore, abalone shells that have completed the final pearl harvesting process can be supplied as a high-end food ingredient for meat production. In other words, meat production can be carried out in addition to pearl production. This point is also significant and will increase the value of abalone pearl farming. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 is a schematic diagram of an abalone shell, viewed from the foot muscle 7 side with the shell facing upwards, excluding the foot muscle. [Figure 2] A perspective view showing the positional relationship between the anterior lobe of the mantle and the respiratory pore located immediately next to it in an abalone shell. [Modes for carrying out the invention]

[0032] The cultivation of bivalves, including Akoya oysters, is primarily carried out by suspending cultivation cages containing oysters with inserted nuclei in the sea. However, as already mentioned, the cultivation method for pearl production using abalone oysters in this invention is completely different from that of Akoya oysters because the feed is different. Abalone farming requires feeding the abalone seaweed, so currently, abalone farming for consumption is mainly carried out in land-based tanks. Similarly, pearl farming using abalone shells can also be done on land, and in fact, land-based farming is preferable and more practical from a cultivation management standpoint. [Examples]

[0033] We purchased commercially available artificially hatched abalone juveniles (shell length approximately 50-60 mm) and cultivated them on land for about six months until they reached a size of approximately 70 mm. The nucleus insertion technique basically uses the same method as that used for Akoya pearl oysters. In this example, a nucleus with a diameter of 3 mm was inserted into the anterior lobe of an abalone mollusk, which was deemed to be of an appropriate size to accommodate the anterior lobe and to be stably maintained without nucleus removal. A piece taken from the mantle of the same species was then attached to the nucleus, and the abalone was returned to a normal land-based aquaculture environment.

[0034] The procedure is as follows. First, when performing the nucleus insertion procedure, it is necessary to anesthetize the abalone shells to facilitate handling. In this example, an aqueous solution of magnesium chloride dissolved in freshwater was used as the anesthetic. The concentration of this magnesium chloride aqueous solution was adjusted so that its specific gravity was the same as that of seawater, and by immersing the abalone shells in this solution for several tens of minutes, the anesthetic effect took place, and the abalone shells became temporarily immobile. For the pieces used for bonding, I selected shells with a strong green color, cut out the mantle using scissors, and created 5 to 10 square pieces measuring 1 to 1.5 mm from each shell. The purpose of the first nucleus insertion was to form a pearl sac. To ensure the formation of a spherical pearl sac even under the vigorous movement of the abalone, a small nucleus with a diameter of 3 mm was used, which could be housed in the anterior lobe, remained intact without detaching, and was stably retained.

[0035] Now, regarding the specific nucleus insertion procedure, in the first attempt, a thin incision was made with a sharp scalpel in the area corresponding to (number 4) in Figure 1 of the anesthetic abalone shell. A thin, sharp scalpel was then inserted through this incision (number 4) into the anterior lobe (number 1) to create a passage for the nucleus. The 3mm diameter nucleus was inserted through this cut (number 4) and advanced to position (number 3). Then, the piece was advanced to the surface of the nucleus (number 2), ensuring that its shell surface was in close contact with the nucleus. The abalone oysters, after the nucleus insertion procedure, were returned to their normal aquaculture environment. The cultivation period varies depending on environmental conditions such as seawater temperature, but it generally takes six months to a year until the first pearl is harvested.

[0036] In the initial trials, the yield was low due to the low level of skill, but even so, we were able to obtain 10 nucleated, perfectly round cultured pearls for every 100 abalone that met the definition of the pearl guidelines in Non-Patent Literature 2. From this, we gained confidence that by inserting the nucleus into the anterior lobe, it is possible to obtain perfectly spherical abalone pearls, which no one had succeeded in doing before, although they were of inferior quality. However, the quality of those pearls was poor; most were deformed or wrinkled, and not of a quality that could be evaluated as a commercial product. Even those that were perfectly spherical needed improvement in terms of sphericity and smoothness. Therefore, the purpose of the first cultivation was not to obtain pearls, but to form pearl sacs for use in subsequent cultivations, with the goal of obtaining perfectly spherical pearls in the second and subsequent cultivations. In these second and subsequent cultivations, pearls with excellent sphericity and smoothness, with minimal deformation and wrinkles, were obtained with a high probability. In other words, it is only through the newly devised method of "repeated nucleus insertion, cultivation, and harvesting multiple times" that "nucleated, perfectly round pearls with superior sphericity and smoothness" can be obtained with a high probability.

[0037] The purpose of subsequent pearl cultivation is to produce perfectly spherical, nucleated pearls with high commercial value. Therefore, the size of the nucleus used must be such that it can be inserted into the empty pearl sac formed during the first cultivation. A nucleus of the same size as, or slightly larger than, the harvested pearl can be used.

[0038] Specifically, for the first pearl harvesting and the second nucleus insertion, one end of the pearl sac was carefully cut open to avoid damaging the pearl inside. Then, using tweezers, the pearl was carefully removed without damaging the abalone shell. After that, a nucleus of the same size as, or slightly larger than, the removed pearl was inserted into the empty pearl sac. After nucleus insertion, the pearls were returned to a normal aquaculture environment and cultivated for approximately six months to a year before being harvested for a second batch of nucleated, perfectly round pearls. During this time, nucleus denucleation after insertion was almost nonexistent.

[0039] The pearls collected from this second and subsequent harvesting were, as expected, nucleated, perfectly round pearls with excellent sphericity and smoothness. In other words, they were perfectly spherical, nucleated, perfectly round abalone pearls with high commercial value. By repeating this process, it becomes possible to produce larger, higher-quality, nucleated, perfectly round pearls with superior sphericity and smoothness with each subsequent iteration, resulting in a high yield. Of course, if the quality is still inferior in the second harvest and there is no expectation of a third pearl harvest, then it is fine to stop cultivating that oyster at that point.

[0040] Evaluation results of the obtained pearls This method of multiple nucleus insertion was performed up to the third time. Table 2 shows a comparison of the size of the nucleus and the size of the resulting abalone pearls obtained by this method. Although it depends on the cultivation period, the diameter of the pearls at harvesting was generally 1.2 to 1.7 times that of the nucleus. [Table 2]

[0041] The sphericity of the obtained pearls was evaluated by measuring the diameters in the three axial directions (X, Y, Z) and using the standard deviation of the relative error = {(measured value - average diameter) / average diameter} relative to the average diameter of each dimension. For each of the 15 pearls obtained from the second and subsequent trials, the standard deviation was calculated, and the average standard deviation of these 15 pearls was 1.60%. Furthermore, for the remaining 13 pearls (excluding two with relatively low sphericity), the average standard deviation was 1.06%. Incidentally, the standard deviation is zero for perfectly spherical pearls. Similarly, when the sphericity of Akoya pearls was measured, the average standard deviation was approximately 0.5-2.0%, although this naturally depends on the quality. From this, it was confirmed that the sphericity of pearls obtained by this method is comparable to that of Akoya pearls. Furthermore, while the smoothness was evaluated visually, all pearls from the second time onward had smooth surfaces free of scratches, wrinkles, or other imperfections. In other words, the method of the present invention has demonstrated that it is possible to cultivate perfectly spherical, nucleated, round pearls using abalone oysters, which was the initial objective. [Industrial applicability]

[0042] Baroque pearls or abalone pearls, which are produced from abalone oysters, play a significant role in the pearl market as high-end pearls due to their unique colors. This invention makes it possible to produce truly "perfectly spherical" nucleated, perfectly round pearls (perfectly spherical abalone pearls) from abalone oysters, which was not possible until now. These perfectly spherical pearls are expected to be accepted as even higher-end pearls than baroque or abalone pearls, thus further expansion of the pearl market can be anticipated. [Explanation of symbols]

[0043] 1. Anterior lobe of the mantle inside an abalone shell 2. Sections (pieces) of mantle epithelial cells collected from other shells of the same species. 3 nuclear 4 cut 5 Priming hole 6 Mantle membrane 7. Breast muscles (leg muscles) 8. Liver The gonads are located surrounding the liver and undergo cycles of growth and decline in accordance with the breeding season. 9 seashells

Claims

1. This method involves inserting a nucleus into an abalone oyster, cultivating it, and then harvesting it to obtain a pearl. However, the insertion site has never been utilized before; it is the narrow anterior lobe of the mantle. Furthermore, the nucleus to be inserted is of a size that can be accommodated within this narrow area and can be stably held without denucleation, thereby obtaining a spherical, nucleated, perfectly round pearl with minimal deformation.

2. A method for producing spherical, nucleated, perfectly round pearls using abalone oysters according to claim 1, characterized in that the first purpose of the first cultivation is to form a pearl sac to be used in subsequent cultivations, and in the second and subsequent cultivations, the sphericity and smoothness of the obtained pearls are improved by using the already formed pearl sac, and further, the size of the nucleus used in the second and subsequent cultivations is the same as or slightly larger than that of the previously obtained pearl, thereby obtaining perfectly spherical, nucleated, perfectly round pearls that are superior in sphericity and smoothness, and which are larger than the previous ones with each subsequent cultivation.

3. A method for performing nucleus insertion, cultivation, and harvesting multiple times as described in claims 1 and 2, characterized in that, at the same time as nucleus insertion, or at different timings, a flattened hemispherical nucleus is inserted between the mantle and shell of the same abalone oyster to obtain multiple perfectly spherical nucleated pearls, and further, after obtaining the last nucleated pearl, a hemispherical pearl attached to the shell is cut off to obtain multiple perfectly spherical nucleated pearls from the same abalone oyster, and finally a hemispherical pearl is obtained.

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