METHOD FOR PRODUCING SPHERICAL PEARLS WITH A CORE USING ABALONE (HALIOTIS)

Abstract

The problem that the present invention aims to solve is to develop a technique that, although long desired, has not yet been achieved. This technique allows the production of spherical pearls with an abalone (Haliotis) nucleus, which exhibit unique and rich shades of green, blue, and other hues not found in other pearl oysters, and are also distinguished by their high sphericity and surface smoothness, giving them a high commercial value.

Description

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

[0001] The method of cultivating pearls from Akoya oysters was developed in Japan over 100 years ago. Since then, it has continued to develop, and today the types of pearl oysters used are no longer limited to Akoya oysters, but include Pinctada maxima, which inhabits other countries. In addition to saltwater pearls, freshwater pearls are also produced using freshwater oysters and are supplied to the global jewelry market. Currently, cultured pearls are produced not only in Japan, but also in Australia, the Philippines, Indonesia, Myanmar, Tahiti, Vietnam, and China.

[0002] The basic principle of cultivating nucleated, perfectly round pearls in bivalves such as Akoya oysters and Pinctada maxima is to insert a nucleus, processed into a spherical shape from the shell of a freshwater bivalve, into the gonad inside the oyster's body. Then, mantle epithelial cells, which are pieces cut from the mantle of the same species of oyster, are attached to the nucleus, and the oyster is cultivated. During this cultivation period, the mantle epithelial cells attached to the inserted nucleus divide and proliferate, enveloping the entire inserted nucleus and forming a pearl sac. Furthermore, the inner surface of this pearl sac secretes nacreous material, and the entire surface of the nucleus is covered with nacreous material, forming a pearl. The above is the basic principle of cultivating nucleated, perfectly round pearls, which was established in Akoya oysters and has been expanded to pearl cultivation in other bivalves.

[0003] The inner surface of the abalone shell, a type of gastropod, possesses distinctive metallic colors such as green and blue, distinct from those of the Akoya pearl, and has an attractive luster that changes in tone depending on the viewing angle. Now, let's touch upon abalone pearls. Occasionally, irregularly shaped natural abalone pearls are found inside abalone shells. Natural abalone pearls are extremely rare and valuable pearls that are created by chance. These baroque pearls from abalone shells, with their beautiful luster, are not spherical, but due to their rarity and unique shape, they are decorated with precious metals and made into very expensive jewelry. Furthermore, there have been no reports of perfectly spherical pearls being found among these natural abalone pearls.

[0004] From this, several attempts have been made to produce round pearls similar to Akoya pearls using abalone shells, but so far, the only products sold under the name "Abalone Pearl" are baroque pearls and hemispherical half pearls with deformed shapes rather than spherical shapes. That is, the cultivation technology for truly spherical nucleated round pearls has not yet been established, and naturally, they are not supplied to the market. In the pearl cultivation industry, spherical pearls are referred to as round pearls, and hemispherical pearls are called half pearls. In the present invention, hereinafter, the expression "half pearl" means a half pearl having a hemispherical surface rather than a semi-circular shape. The present invention provides a cultivation technology that enables the production of "truly spherical" nucleated round pearls from abalone shells, which have not been successfully produced so far.

[0005] Now, the definition of nucleated round pearls will be briefly described. In Non-Patent Document 2, "Pearl Guidelines 2020", on page 19, round pearls are described as "pearls whose entire surface is covered with nacre". That is, round pearls do not necessarily mean that their shape is truly spherical. Therefore, in the present invention, in order to emphasize that the shape is truly spherical, the expression "truly spherical nucleated round pearls" is used. Also, on page 74, it is stated that "the material of the nucleus used for nucleated pearl cultivation is limited to the nacre layer of the shell of freshwater bivalves, and no other materials are allowed." The reason is also described. Regarding the "method for obtaining truly spherical nucleated round pearls" of the present invention, although the material of the nucleus is not limited in any way, from the perspective of the strength and quality of the obtained pearls, naturally, the nucleus obtained from freshwater bivalves should be used in accordance with the pearl guidelines.

[0006] First, pearl cultivation involves inserting a nucleus into the body of a pearl oyster and allowing nacre to form on its surface (this is referred to in the industry as "making the pearl form"). However, simply inserting a nucleus into the pearl oyster is not enough to "make the pearl form." It is necessary to attach a piece (a section) of mantle epithelial cells, taken from the same type of oyster that has the function of secreting nacre, 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, that is, 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 attachment of the piece, the stable maintenance of the attachment between the inserted nucleus and the piece, and cultivation are all 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 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. During this time, a pearl sac forms inside the oyster, and then the nacreous layer forms on the inside (the surface of the inserted nucleus). In contrast, gastropods such as abalone and turban shells feed on seaweed such as wakame and kelp, and to hunt for these, the shells need to actively move around in search of food. Also, when abalone senses danger, they cling firmly to rocks and 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. 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 the anesthetic.

[0009] Now, while this anesthesia method makes the nucleus insertion 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 nuclei are inserted to obtain pearls. 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 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 oysters differs significantly from that of Akoya oysters. The gonads are closely connected to internal organs (such as the liver), making it technically extremely difficult to insert a nucleus into the gonad without damaging the internal organs. In abalone that overcome this difficulty and can be successfully cultured without nucleus loss, a pearl sac forms within the gonad. However, this pearl sac itself is subjected to deformation due to pressure from the leg muscles. As a result, the pearl formed within this deformed pearl sac, despite the insertion of a perfectly spherical nucleus, becomes a deformed pearl, i.e., a baroque pearl.

[0011] Under these circumstances, in Japan, various measures have been taken to prevent the inserted nucleus from dislodging due to 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 dislodging of the inserted nucleus and to suppress the movement of the nucleus 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 semi-spherical 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 traces of thread used to prevent the piece and nucleus from separating." In other words, a perfectly spherical, nucleated, round pearl without deformation or damage has not yet been obtained. Patent Document 5 states that the gonad atrophies during the nucleus insertion period, creating a gap between it and the mantle, and that the nucleus is inserted into this gap. However, the resulting pearls are still baroque pearls. Patent document 6 describes a pearl cultivation method in Chile, in which the nucleus insertion site is the gonad, and in order to prevent nucleus removal, the incised area is sutured with absorbable sutures to 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 the abalone for about 1.5 to 2.5 years, the pearl portion is cut out from the shell to obtain a semi-circular pearl. Currently, this technology is used to produce semi-circular abalone cultured pearls, which are 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.

[0014] Japanese Patent Publication No. 1974-107888 describes a method of cultivating pearls using abalone as the mother oyster, making a hole of appropriate size in the upper part of the dorsal gonads of the mother oyster, and fixing a nucleus to be inserted into the oyster body using wire or the like. Japanese Patent Publication No. 1981-154936 describes a method in which a nucleus and piece are inserted into the inside of the abalone's mantle so that they are in contact with each other, then the abalone is placed in a cylinder and cultivated in seawater to form a pearl. Japanese Patent Publication No. 2018-110553 describes a method in which a nucleus is inserted from the head side of the abalone between the shell and the mantle using a straw-shaped tube to form a semi-formed pearl. Japanese Patent Publication No. 1986-15636 describes a method for forming a pearl by drilling a hole in the mantle of an abalone shell at the attachment point where the mantle attaches 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 through a hole drilled in the shell using this nylon fishing line. However, this patent has been deemed withdrawn, and no reports of actually obtaining a perfectly spherical pearl have been found since then. Japanese Patent No. 7418626 (2024) describes a method for inserting a nucleus into the gonads of an abalone shell, but stating that inserting a nucleus into these gonads is extremely difficult. Therefore, the method involves inserting the nucleus into the gap between the mantle and the gonads that forms after sperm or eggs have been released and the gonads have contracted. However, the resulting pearl is not perfectly spherical, but rather a deformed baroque shape. International patent application WO2016183695 describes a method developed in Chile for obtaining pearls from abalone. The method involves making an incision in the abalone's gonad and inserting a nucleus; however, the movement of the leg muscles makes the inserted nucleus prone to dislodgement. Therefore, this method prevents dislodgement by suturing the incision with absorbable sutures. However, even in this case, the resulting pearls are deformed baroque pearls. Pearls produced using this technology are sold under the brand name (Atacama Pearls). https: / / atacamapearls.com /

[0015] Pearl cultivation: Pages 185-188 of the 1987 edition mention Hiroshi Uno's cultivation of hemimorphous and round pearls from abalone. Hemimorphous pearls are formed by drilling a hole large enough to accommodate a hemimorphous nucleus from the outside of the shell, and then fixing the nucleus with a fixative after insertion. The Pearl Promotion Association's "Pearl Guidelines 2020," page 59, contains definitions of pearls, cultured pearls, and nucleated round pearls: https: / / pearlexperts.net / wp-content / uploads / 2021 / 04 / pearl_guidelines_2020.pdf The Fall 1998 issue of GEMS & GEMOLOGY, the journal of the Gemological Institute of America (GIA), describes the cultivation of abalone pearls in New Zealand. According to this document, a flat disc with one side spherical is used as a nucleus and pressed between the mantle and shell of the abalone pearl before cultivation. This causes a nacreous layer, identical in composition to the inner surface of the shell, to form on the surface of the inserted nucleus. The resulting pearl is integrated with the shell, and a circular pearl portion is cut from this shell and further shaped through cutting to create a semi-formed pearl.

[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.

[0017] This invention was made to solve the aforementioned problems. First, to suppress the vigorous leg muscle movements of the abalone oyster 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 embodiment, 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 site for nucleation 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 considered before. This area is a narrow region between the respiratory pore (number 5 in Figures 1 and 2) and the edge of the shell, and as shown in Figure 2, it is the part where the mantle, which is normally spread in a planar manner, bends towards the shell 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. Specifically, in this anterior lobe, the size of a nucleus that does not dislodge even under the pressure of the foot muscle is only about 3 mm in the case of an abalone shell 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, its small size will result in low commercial value. In other words, even if pearls are cultivated using this site as the nucleus insertion site, there is no economic benefit to doing so if the commercial value is low. This is thought to be one of the reasons why nucleus insertion has not been performed in this site 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 a smaller-than-usual nucleus that can be housed here. In other words, by using a nucleus that can be housed in this anterior lobe, it is less susceptible to compression by the foot muscles, and nucleus removal 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 is desirable to insert the largest possible nucleus, but this is pointless if the nucleus is removed. Similarly, even if small pearls are obtained, they are meaningless if they have low commercial value. Furthermore, after inserting this small nucleus, it takes approximately one month for the pearl sac to form from the piece. During this time, the pearl is constantly subjected to pressure from the movement of the leg muscles, which causes deformation and wrinkles in the forming pearl sac, and these deformations and wrinkles are reflected in the surface of the pearl formed within the pearl sac. 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 nucleus insertion are not only small in size, but also of considerably lower quality in terms of sphericity and smoothness.

[0023] While spherical pearls are produced, their value is low. This is a dilemma. This invention resolves this dilemma by repeating the nucleus insertion, cultivation, and harvesting (pearl collection) process multiple times, as described below. In other words, in abalone pearl cultivation, where only deformed baroque pearls or hemiform pearls have been obtained until now, this invention provides a method for producing (cultivating) perfectly spherical abalone pearls that also have high commercial value.

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

[0025] After inserting the nucleus 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 previously extracted pearl, a moderate tension acts on the pearl sac immediately after insertion. This also corrects any wrinkles or sagging in the pearl sac, resulting in a larger, perfectly spherical, nucleated pearl with superior sphericity and smoothness compared to the previous one. Therefore, for subsequent nucleus insertions, it is preferable to use a nucleus that is the same size as, or slightly larger than, the previously extracted pearl, considering that the size of the anterior lobe has also increased due to the growth of the oyster. Even when inserting a nucleus of the same size as the previously extracted pearl, the nacreous layer forms within the pearl sac, so the size of the resulting pearl will be larger 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, 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 high-value pearls, but to form pearl sacs for use in subsequent cultivations, with the aim of obtaining high-value pearls in the second and subsequent cultivations. Of course, it is possible to select pearls with relatively good sphericity or unique shapes that are considered to have high commercial value from those harvested in the first cultivation 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] [Supplement based on Rule 26 17.04.2025] Naturally, this method of repeating nucleus insertion, cultivation, and harvesting multiple times is not limited to the second time, but similarly, pearl cultivation can be continued for the third, fourth time, and so on. In this case, as mentioned above, with each subsequent time, a larger pearl will be obtained than the one obtained in the previous time. This is also a major feature of the present invention. First, a major feature of the present invention is that the nucleus insertion site is the anterior lobe. Furthermore, although nucleus insertion, cultivation, and harvesting are repeated multiple times, a pearl sac is formed in the first cultivation, and in the second and subsequent cultivations, this pearl sac is used to obtain a perfectly spherical, nucleated, round pearl. The features of the method of the present invention are summarized in 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.

[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 using a size that the anterior lobe can accommodate, prevent nucleus removal from occurring, and maintain stably, a pearl sac is formed that allows for the production of pearls with superior sphericity and smoothness from the second time onward. 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 size as the previous one, or slightly larger, for subsequent insertions, it becomes possible to obtain larger, more perfectly round, nucleated pearls with superior sphericity and smoothness with each repeated 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 spherical, nucleated, round pearls with excellent sphericity and smoothness at a high yield of at least 90%. 4. By performing nucleus insertion into the anterior lobe and insertion of a flattened hemispherical nucleus between the mantle and the shell in parallel, multiple perfectly spherical, nucleated, round pearls can be obtained during the cultivation period. Furthermore, by removing the hemispherical pearls that have grown attached to the shell at the end, 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 round and hemispherical pearls simultaneously. 5. In addition, abalone shells that have finished the final pearl harvesting can be supplied as a high-grade food ingredient for meat. In other words, meat production can be carried out in addition to pearl production. This point is also significant and increases the value of abalone pearl cultivation.

[0031] Figure 1 is a schematic diagram of an abalone shell, with the shell facing upwards and the foot muscles 7 removed, viewed from the foot muscle side. It is a perspective view showing the positional relationship between the anterior lobe of the mantle and the respiratory pore located immediately next to it within the abalone shell.

[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, in the case of pearl production using abalone oysters as described above, the feed is different, so the cultivation method is completely different from that of Akoya oysters. In abalone cultivation, it is necessary to feed the abalone with seaweed, so currently, abalone for consumption is mainly cultivated in tanks on land. Therefore, pearl cultivation using abalone oysters can also be done on land, and in fact, land cultivation is preferable and more practical from the standpoint of cultivation management.

[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 method used for Akoya pearls. In this example, a nucleus with a diameter of 3 mm was inserted into the anterior lobe of the abalone, which was of an appropriate size to accommodate the anterior lobe and to be held stably without nucleus loss. 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 cultivation environment.

[0034] The procedure is described below. First, to facilitate handling the abalone during the nucleus insertion process, it is necessary to anesthetize the abalone shell. 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 shell in this solution for several tens of minutes, the anesthetic effect took place, and the abalone shell became temporarily immobile. For the pieces used for adhesion, shells with a strong green color were selected from among the shells, and the mantle was cut out using scissors to create 5 to 10 square pieces of 1 to 1.5 mm from one shell. The purpose of the first nucleus insertion is the formation of a pearl sac, so in order to reliably form a spherical pearl sac even under the vigorous movement of the abalone shell, the size of the nucleus used was such that it could be housed in the anterior lobe, would not detach, and could be stably held, and a small nucleus with a diameter of 3 mm was used.

[0035] Now, regarding the specific nucleus insertion procedure, in the first instance, a thin incision was made with a sharp scalpel at the area corresponding to (number 4) in Figure 1 of the anesthetized abalone oyster. 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 aforementioned 3mm diameter nucleus was inserted through this incision (number 4) and advanced to the position of (number 3). After that, 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 oyster that had undergone the nucleus insertion procedure was returned to the normal aquaculture environment. The cultivation period varies depending on environmental conditions such as seawater temperature, but it is generally six months to one 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 these pearls was such that most were deformed or wrinkled and were not of a quality that could be evaluated as a commercial product. Even if they were perfectly spherical, their sphericity and smoothness needed to be improved. Therefore, the purpose of the first cultivation was not to obtain pearls, but to form pearl sacs for use in subsequent cultivations, and to obtain perfectly spherical pearls in the second and subsequent cultivations. In these second and subsequent cultivations, pearls with less deformation and wrinkles, and superior sphericity and smoothness 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, round 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. Using tweezers, the pearl was carefully removed without damaging the abalone oyster, and then a nucleus of the same size as, or slightly larger than, the removed pearl was inserted into the empty pearl sac. After insertion, the abalone was returned to a normal cultivation environment and cultivated for approximately six months to a year before being harvested for the second batch of nucleated, perfectly round pearls. During this process, nucleus detachment after insertion was almost nonexistent.

[0039] The pearls harvested from the second harvest onward were, as expected, perfectly round, nucleated pearls with excellent sphericity and smoothness. In other words, they were perfectly round, nucleated abalone pearls with high commercial value. By repeating this process, it becomes possible to produce larger, higher-quality, nucleated, round pearls with superior sphericity and smoothness with a high yield. Of course, if the quality is still poor in the second harvest and there is no expectation of a third harvest, then the cultivation of that oyster can be stopped 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 nucleus size and the size of the obtained pearls for the abalone pearls obtained by this example. Although it depends on each cultivation period, the diameter of the pearls at harvesting was generally 1.2 to 1.7 times that of the nucleus insertion period.

[0041] The sphericity of the obtained pearls was evaluated by measuring the diameter in three axial directions (X, Y, Z) and calculating the standard deviation of the relative error relative to the average diameter = {(measured value - average diameter) / average diameter}. When this standard deviation was calculated for each of the 15 pearls obtained from the second time onward, the average standard deviation of the 15 pearls was 1.60%. Furthermore, after removing two pearls with relatively low sphericity, the average standard deviation for the remaining 13 pearls was 1.06%. Incidentally, the standard deviation is zero for perfectly spherical pearls. When the sphericity of Akoya pearls was measured in the same way, the average standard deviation was approximately 0.5 to 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. As for smoothness, this is a visual evaluation, but all pearls from the second time onward had smooth surfaces without any traces of scratches or wrinkles. 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.

[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.

[0043] 1. Anterior lobe of the mantle inside an abalone shell. 2. Section (piece) of mantle epithelial cells collected from another shell of the same species. 3. Nucleus. 4. Cross section. 5. Respiratory pore. 6. Mantle. 7. Foot muscles. 8. Liver. The gonads surround the liver and undergo cycles of growth and decline in accordance with the breeding season. 9. Shell.

Claims

1. A method for producing pearls using abalone oysters, characterized by the following: inserting a nucleus into an abalone oyster, cultivating it, and harvesting the pearl afterward, but using the anterior lobe of the mantle, a narrow trough-shaped region that has never been used before, as the insertion site for the nucleus, making a thin incision in the anterior lobe of the mantle with a sharp scalpel to form an opening, and inserting a thin, sharp scalpel into the back of the anterior lobe of the mantle through this opening to create a passage for the nucleus to be inserted, and making the nucleus to be inserted a size that can accommodate the aforementioned passage in the narrow trough-shaped region and can be stably held without denucleation, thereby obtaining a spherical, nucleated, perfectly round pearl with minimal deformation.

2. A method for producing 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 the second and 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 the nucleus used in the previous cultivation, thereby obtaining a perfectly spherical, nucleated, round pearl that is superior in sphericity and smoothness, and is larger than the previous one with each subsequent cultivation.

3. A method for producing pearls using abalone oysters according to claim 2, characterized in that, in a method in which nucleus insertion, cultivation, and harvesting are performed multiple times, a flattened hemispherical nucleus is inserted between the mantle and shell of the same abalone oyster in parallel with or at different times during nucleus insertion, thereby obtaining multiple perfectly spherical nucleated pearls, and further, after obtaining the last perfectly spherical nucleated pearl, a hemispherical pearl attached to the shell is cut off, thereby obtaining multiple perfectly spherical nucleated pearls from the same abalone oyster, and finally obtaining a hemispherical pearl.