WO2017047610A1 - Pearl orb and method for manufacturing same - Google Patents

Abstract

Provided are a magnetic pearl orb and a method for manufacturing the same. This method for manufacturing a pearl orb is characterized in that a pre-magnetized magnet piece that has been subjected to an anticorrosion step is inserted inside a pearl oyster, a pearl layer is then allowed to grow around the magnet piece as a kernel, and after the magnet piece covered with the pearl layer is taken out of the pearl oyster, the magnet piece is magnetized. This pearl orb is characterized in comprising a magnet piece subjected to an anticorrosion step, and a pearl layer that is formed around the magnet piece as a kernel.

Description

Pearl ball and method of manufacturing the same

The present invention relates to a pearl ball and a method of manufacturing the same, and more particularly to a pearl ball having a nacre layer formed around a magnet piece as a core and a method of manufacturing the same.

Pearls with a beautiful luster, also called "drops of the moon" or "mermaid's tears", have long been prized as gems around the world.
Natural pearls are produced by accidental entry into the shell of a shell, which secretes shell components, but the amount of production is extremely small and it is highly valuable.
On the other hand, most of those generally on the market are cultured pearls. This is formed by inserting a nucleus cut into a spherical shape from a shell of a bivalve shell together with an outer membrane into a pearl oyster body to form a nacreous layer.
For pearl farming, the mother shellfish is grown, the nucleus is put in the mother shell shell, and the shellfish subjected to surgery for nucleus insertion is cured and then cultured in a cage hanging on the shore of the sea, and after about 6 to 8 months It takes care of harvesting and taking out pearls, and it usually takes 4 years from breeding of mother shellfish to taking out of pearls.
The core to be inserted into the mother shell is mixed with a core consisting of a natural product obtained by processing a shell of the same or different shellfish as the mother shell, and a substance close to a shell component, shaped into a sphere, and fired to be artificial. Methods using a core are known (see, for example, Patent Documents 1 to 4).

If pearls can be cultured with the magnetic pieces as the core, pearls with magnetic force will be formed. Although pearls are sometimes used alone as pendants and earrings, they are often used as necklaces of pearl beads in which pearls are connected in a straight line, and are used as luxurious ornaments wound in layers. There are also many things. Under these conditions of use, pearls with magnetic force, combined with chains (or wires) of accessories with magnetism that respond to magnetism, enable new decorations that have not been achieved before, making possible novel accessories It is expected to be an open-minded person.
The biggest obstacle to aquaculture of pearls with magnetic pieces as the core is the problem of rusting. Since many pearl oysters are cultured in seawater, if magnets are inserted directly into the pearl oyster's body, there is a problem that not only the formation of the nacreous layer will occur immediately but also the mother shell will die.

JP 2012-13033 A JP 2008-22866 A Japanese Patent Application Laid-Open No. 11-75609 Japanese Patent Application Laid-Open No. 07-115867

The present invention has been made to solve the above problems, and its object is to provide a pearl ball having a magnetic force and a method for producing the same.

The method for producing pearl beads according to the present invention, which has been made to achieve the above object, is to insert a pre-magnetized magnet piece with anti-corrosion measures into the inside of a pearl shell, and then use the magnet piece as a core to make a nacre. It is characterized in that it is made to grow after surrounding magnet pieces are taken out from the pearl shell and covered with a nacreous layer, and then magnetized.

It is preferable that the anticorrosion measure given to a magnet piece is plating or resin coating.
The plating may be one or more selected from electroplating, chromium plating, electroless plating, hot-dip plating, vacuum deposition, insoluble anode and electroforming.

It is preferable that the anticorrosion measure is a resin coating, and the surface of the resin-coated magnet piece is further coated with a resin containing calcium carbonate.
After nacre growth, it is preferable to perform a drilling process through the nacre and the magnet pieces.

The pearl ball of the present invention is characterized by comprising a magnet piece subjected to anti-corrosion measures and a nacre layer formed around the magnet piece as a core.

It is preferable that a magnet piece is 1 type chosen from the group which consists of a ferrite magnet, a samarium cobalt magnet, and a neodymium magnet.
The anti-corrosion measure is plating, and the plated metal is preferably one or more selected from the group consisting of gold, silver, copper, platinum, tin, chromium, nickel, and alloys thereof.
It is preferable that resin is further coated around the metal-plated magnet piece.

It is preferable that the anti-corrosion resin is a coating, and the magnet piece is coated with a resin around its periphery.
The surface of the magnet piece coated with resin may be further coated with another type of resin.
The surface of the resin-coated magnet piece may be further coated with a resin containing calcium carbonate.
It is preferable that the magnet piece in which the nacreous layer is formed has a hole formed through the nacreous layer and the magnet piece.

According to the present invention, a magnet piece with anti-corrosion measures is inserted into the inside of pearl oysters, and this pearl oyster is cultured to form a nacreous layer around the magnet pieces, and then a nacreous layer is formed. By harvesting the pieces and magnetizing them, pearl balls having magnetic force can be produced.
It is possible to produce a decorative pearl ball having a through hole and having a magnetic force, by growing a nacreous layer around a magnet piece as a core and then performing a drilling process to penetrate the nacreous layer and the magnet piece. it can. The pearl ball having the through hole and the magnetic force can be placed as an ornament at an arbitrary position of the chain or the wire by combining it with an accessory such as a chain or a wire having magnetism responsive to the magnetic force. It enables the design of new accessories that have not been made before, and has the effect of opening up the possibility of novel decoration.

In the method of producing pearl beads according to the present invention, after inserting an unmagnetized magnet piece with anti-corrosion measures into the inside of the pearl shell, the pearl shellfish is cultured and the pearl layer is grown around the magnet piece as a core It is characterized by
For the purpose of cultivating pearl beads, a pearl oyster is usually used as a mother shellfish, but in Okinawa, a black butterfly mussel and in Amami Oshima, a mussel mussel is used as a mother shellfish and is used for aquaculture abroad When the pearl oysters are combined, a very large number of oysters are used.

In the present invention, pearl-making shellfish are referred to as pearl shellfish, but basically, most shellfish having a nacreous layer can produce pearls.
In the present invention, pearl snails include pearl oysters, Icelandic gai, squirrel abalone, abalone, mussels, squirts, snails, nautiloid snails, snails, snails, snails, snails, snails, snails, snails, snails, snails Gata German Mai, Sara Saba Tate, Shisira tilay, White-lipped clam, White-backed clam, Red-handed oysters, oysters, oysters, snails, snails, snails, snails, snails, snails, snails, blow-lip snails,ニ コ ニ コ, ガ イ ガ イ, ビ 、 ホ, シ シ 、 カ ラ, マ イ イ マ イ, ベ ベ, ス レ, ゼ ラ ン, ゼ 、, コ ウ ガ イIt can be exemplified European ball millet, and European Gila brat. In the present invention, one or more selected from these groups can be pearl oysters.

In the culture of pearls, the mother shellfish are grown, the pearl nucleus that is the core of the pearl bead is inserted into the inside of the mother shellfish, and after shelling the shellfish which has undergone the nucleus insertion surgery for a certain period, Under a suitable environment, for example, the fish may be cultured in a cage suspended on an offshore shore. The aquaculture period should be continued from half a year to one year according to the growth of the mother shellfish. In the case of pearl oysters, it can be harvested 6 to 8 months after the nucleus insertion surgery.
The present invention is characterized in that the core to be inserted into the mother shell is a magnet piece before magnetizing which has been subjected to anti-corrosion measures. The magnet piece before magnetizing inserted into the mother shell is preferably a kind selected from the group of magnet pieces having a component constitution to be a ferrite magnet, a samarium cobalt magnet, and a neodymium magnet after magnetizing.
Ferrite magnets can be made by molding and burning iron oxide as a main raw material. Samarium cobalt magnets can be made by molding and burning samarium and cobalt as raw materials. A neodymium magnet can be formed and sintered by using neodymium, iron and boron as main components.
In the present invention, any of these magnets can be preferably used.
Any magnet can be molded into a free shape. The pearl ball of the present invention can produce various shapes of pearl balls because the shape of the magnet piece can be made free (for example, heart-shaped, star-shaped, etc.), and its decoration method is also conventionally Because it can be decorated in a different state, it can provide a completely new accessory design.

The biggest problem in using a magnet before magnetizing as a pearl core is that rust occurs on the core magnet piece. In particular, since pearl oysters are blisters and grow from brackish water area to seawater area in many cases, magnet pieces inserted inside pearl oysters are also exposed to these salt waters, causing rust to occur quickly become.
When rust occurs in the core, not only nacreous layer is not formed, but there is a possibility that the mother shellfish may be killed by the eluted metal ions. Also, even if the nacreous layer is formed, the surface of the magnet is discolored, and no pearl ball that can withstand the decoration is produced.
As a method of rustproofing the magnet piece, there are a method of plating the magnet piece and a method of resin coating the magnet piece.
Plating is a technique that covers easily oxidizable metals with metal that is not easily oxidized, and is a technology that has been used for a long time. As a plating method, electroplating, chromium plating, electroless plating, hot-dip plating, vacuum evaporation, insoluble anode, electroforming, etc. are known, but any of these methods can be used in the present invention. , One or more can be selected according to the situation.

The metal to be plated is preferably at least one selected from the group consisting of gold, silver, copper, platinum, tin, chromium, nickel, and alloys thereof.
Magnet strips plated with these metals will have a metallic luster on the surface. For example, the surface of a gold-plated magnet piece glows gold by electroplating with potassium cyanide as an electrolyte, the copper-plated magnet piece is copper-colored, and the silver, platinum, tin, chromium, nickel-plated magnet piece is silver-colored With a metallic luster.
When the magnet pieces having these metallic lusters are inserted into the inside of pearl shells and the nacreous layer is grown around the magnet pieces as cores, the nacreous layer is formed on the surface of the metallic luster pieces and while maintaining the brightness Even pearls with an elegant (or elegant, profound) feel can be produced with a reduced glare.

As another method of preventing rusting of the magnet piece, there is a method of resin-coating the magnet piece. The resin coating method may be any of conventionally used methods such as a spray method, a paint method, a film wrap method, an immersion method, and an insert injection method.
Resins that can be coated on magnet pieces include polyethylene, polypropylene, polystyrene, acrylic resin, methacrylic resin, AS resin, ABS resin, ABS resin, polyurethane resin, general-purpose plastic such as polyvinyl chloride resin, polyamide 6, polyamide 66, polycarbonate, polyacetal, polyethylene Examples include general engineering plastics such as terephthalate, polybutylene terephthalate and modified polyphenylene ether, and super engineering plastics such as polyarylate, polysulfone, polyethersulfone, polyethersulfone, polyamideimide, polyetherimide, polyphenylene sulfide, polyetheretherketone, polyimide, and fluorine resin. be able to.
The resin coated on the magnet piece may be a thermosetting resin such as phenol resin, urea resin, melamine resin, epoxy resin, silicone resin, unsaturated polyester, and polyurethane.
Among them, general purpose plastics such as polyethylene, polypropylene, polystyrene and methacrylic resin, and general purpose engineering plastics such as polyamide 6, polyamide 66, polycarbonate, polyacetal and polyethylene terephthalate can be preferably used.
It is also possible to use natural polymers such as persimmon juice, lacquer, jaundice, or rattan as a resin other than the resin for coating the non-magnetized magnet pieces.

The plated, premagnetized magnet pieces can also be further coated with the above resin. By further resin-coating the plated magnet pieces, it is possible to prevent discoloration (discoloration) of the surface having a metallic luster.
In addition, it is possible to coat the surface of the magnet piece before magnetization which is coated with the above-mentioned resin with a resin containing another kind of resin or filler.
If the resin is dual coated, a hydrophilic resin can be used for the outer coating.
In the present invention, examples of hydrophilic resins include polyvinyl alcohol, polyethylene glycol, polyvinyl acetate resin and sodium polyacrylate. Among them, polyethylene glycol can be preferably used.
By covering the surface of the core inserted inside the pearl shell with a hydrophilic resin, the percentage of the core staying inside the pearl shell is improved and the pearl layer is easily formed, so the yield of pearl beads is increased. It can be improved.

It is also possible to further coat the resin containing the filler on the surface of the magnet piece before magnetizing the resin is coated.
In the present invention, as fillers to be mixed with the resin coated on the outside, shell components such as calcium carbonate and calcium phosphate, apatite, talc, silica, natural ores such as clay, titanium oxide, aluminum powder, glass beads, mica, zirconia And the like. Above all, calcium carbonate can be preferably used because it can not only improve the percentage of nuclei staying inside the pearl oyster but also increase the transparency of the pearlescent beads on which the nacreous layer is formed.
The paint may be mixed with the resin to be coated on the outside. By mixing paints of various colors, it is possible to produce pearlescent beads of a color that has not existed before.
When aiming at a pearl of a true sphere, it is preferable to use a disc and mixed sand to finish the core of a true sphere by using a disc and mixed sand before magnetizing.

Pre-magnetized magnet pieces with anti-corrosion measures are inserted into the inside of pearl oysters by nucleus insertion surgery and cultured in the natural environment, but this process is identical to the production process of cultured pearls The explanation is omitted.
Furthermore, after a certain period of aquaculture, the step of taking out and sorting the pearls by beaching is also the same as the production process of the cultured pearls, so the description thereof is omitted.
The magnet piece before magnetizing, on which the sorted nacreous layer is formed, is subjected to a drilling process through the nacreous layer and the magnet piece, and a through hole is formed at the center thereof.
The magnet piece before magnetizing which has the nacreous layer in which the through-hole was formed can be magnetized by exposing to a strong magnetic field.

The method of magnetization is determined by the number of magnetic poles to be produced, but in the case of the present invention, magnetization by a magnetizing coil is appropriate. Magnetization by the magnetizing coil is performed by using a capacitor type magnetizing power supply (pulse type power supply) that discharges the charge stored in a large capacity capacitor instantaneously, and when a large current is supplied to the magnetizing coil and yoke, the magnetizing is performed. A magnetic field is generated in one direction along the longitudinal direction of the magnetic coil, and a magnet piece placed in the magnetized coil is magnetized by a magnet having a pair of N pole and S pole.
At this time, the positions of the N pole and the S pole are determined by the orientation of the magnet piece before magnetization installed in the magnetizing coil. In general, it is preferable that the through hole opened in the magnet piece before magnetization be installed so as to overlap with the radial direction of the magnetizing coil so that the through hole penetrates the equator after magnetization.
Temporarily, when the through hole is magnetized so as to penetrate the N pole and the S pole, when a plurality of pearl beads are chained in one accessory chain, the pearl beads will either attract or repel each other as expected There is a possibility that the decoration can not be done. If the through hole penetrates the equator, even if the pearls attract or repel each other due to the magnetic force, the distortion of the magnetic field can be eliminated by rotating the pearls around the accessory chain. it can.

Example 1: Production of a neodymium magnet piece
1 kg of a neodymium magnet demagnetized at about 500 ° C. was crushed with an impact type crusher (manufactured by Earth Technica Co., Ltd .; trade name: Super Thunder, model KMO0702R) to form a sand having a particle diameter of 100 to 500 μm. Furthermore, using a pulverizer (manufactured by Hosokawa Micron Corporation: Spiral jet mill AS 140), the mixture was pulverized to a fine particle size of 3 to 5 μm. The fine powder was formed into a sphere in a magnetic field of 11 kOe by applying a pressure of 100 N · m with a dry granulator (manufactured by Freund Sangyo Co., Ltd .: roller compactor TF9). The particle size of the molded article was a sphere of 6 mm in diameter. The molded spherical magnet pieces were sintered at 1100 ° C. for 3 hours using an internal-combustion rotary kiln (manufactured by Takasago Kogyo Co., Ltd.), and subsequently heat-treated at 500 to 900 ° C. for 6 hours. The heat-treated magnet pieces were processed with river sand as a polishing agent on a rotating polishing plate to make the shape into a true sphere.

[Example 2: Plating of a neodymium magnet piece]
A half amount of the magnet pieces processed in Example 1 were subjected to nickel plating by a nickel sulfamate plating method in an electrolytic bath. The pieces of neodymium magnet pieces before magnetizing which had been plated with nickel were subjected to shape inspection, and the rejected products were subjected to finishing processing until they became true spheres by using a metal sand as a polishing agent on a rotating grinder again. One hundred magnetic pieces that passed the inspection were inserted into the pearl oyster one by one. After cultured for 8 months, we performed beach harvesting (harvest) and examined the survival rate of mother shellfish, recovery rate of pearl beads, and quality of pearl beads.

Example 3 Resin Coating of Plated Neodymium Magnet Pieces
The surface of the neodymium magnet piece plated in Example 2 was spray-coated with an isocyanate-curing acrylic resin (manufactured by DIC Corporation: trade name Acridic, part number A-801-P). An acrylic resin-coated neodymium magnet piece before magnetizing was inspected, and 100 pieces of the passed magnet piece were inserted into the inside of the pearl oyster. After the culture as in Example 2, the survival rate of mother shellfish, the recovery rate of pearl beads, and the quality of pearl beads were examined.

[Example 4: Resin coating of neodymium magnet piece]
Half of the magnet pieces processed in Example 1 were coated with polyethylene by a fluid immersion method. The surface of the magnet is obtained by immersing the magnet piece heated to 150 ° C. for 5 seconds while putting polyethylene powder in the resin powder tank and blowing compressed air from below to flow the powder into the tank. Was coated with polyethylene. The shape of the polyethylene-coated pre-magnetized neodymium magnet piece was inspected, and 100 pieces of the passed magnet piece were inserted into the inside of the pearl oyster. After the culture as in Example 2, the survival rate of mother shellfish, the recovery rate of pearl beads, and the quality of pearl beads were examined.

[Example 5: Hydrophilic resin coating of polyethylene coated neodymium magnet piece]
The surface of the neodymium magnet piece coated with polyethylene in Example 4 was further coated with polyethylene glycol. The coating was further coated with polyethylene glycol on the outside of the polyethylene-coated magnet piece by spraying molten polyethylene glycol. The shape of the magnet piece was inspected, and 100 of the passed magnet pieces were inserted into the inside of the pearl oyster. After the culture as in Example 2, the survival rate of mother shellfish, the recovery rate of pearl beads, and the quality of pearl beads were examined.

[Example 6: Coating a polyethylene-coated neodymium magnet piece with a resin containing a calcium carbonate filler]
The surface of the neodymium magnet piece coated with polyethylene in Example 4 was further coated with a vinyl chloride resin containing a filler of calcium carbonate. Calcium carbonate filler (Shiroishi Calcium Co., Ltd .: particle size 2 to 20 μm) surface-treated with stearic acid is mixed at a ratio of 60% by weight with respect to 100 parts by weight of polyvinyl chloride resin (manufactured by Shin-Etsu Chemical Co., Ltd.) The surface layer was formed by insert injection molding. The shape of the magnet piece coated with a polyvinyl chloride resin containing calcium carbonate was further examined on the outside of the polyethylene coated magnet piece, and 100 of the passed magnet pieces were inserted into the inside of the pearl oyster. After the culture as in Example 2, the survival rate of mother shellfish, the recovery rate of pearl beads, and the quality of pearl beads were examined.

Comparative Example 1: Inserting a nucleus produced from bivalve shells into pearl oysters
In place of the magnet pieces of the above-mentioned Examples 2 to 6, one hundred spherical core-shaped cores of 6 mm in diameter obtained by grinding and processing bivalve shells of the mussel belonging to the Mississippi River in the United States were inserted inside the pearl oyster. As in Examples 2 to 6, aquaculture was carried out for 8 months in a cage suspended on a boat floating offshore. After eight months, the beach was fried (harvested) to examine the survival rate of the mother shellfish, the recovery rate of the pearl beads, and the quality of the pearl beads.

The results of the tests of Examples 2 to 6 and Comparative Example 1 are shown in Table 1.
The survival rate of the mother shellfish was calculated based on the number of mother shellfish at the beginning of aquaculture, counting the number of mother shellfish that lived in the coral hanging on the shore of the sea for 8 months. The pearl bead recovery rate was calculated by dividing the number of pearl beads collected after beaching by the number of mother shells at the beginning of aquaculture. The difference between the survival rate of mother shellfish and the recovery rate of pearl beads corresponds to the proportion of mother shellfish from which nuclei were dropped during the aquaculture process.
Pearl beads are sorted according to color, shape, and scratches, and the quality equivalent to the superior pearls of "brightness,""color," and "rolling" is "excellent," the quality of the grade that can be processed into a series of gemstone necklaces "Good", the quality of the grade that can be processed into multiple rows of beads necklace is "OK", and the one that can not be processed even when processed is measured as "NO", and divided by the number of mother shellfish at the beginning of aquaculture Calculated. However, with regard to the evaluation of “excellent”, Comparative Example 1 is a comprehensive evaluation of “brightness”, “color”, and “roll”, and in Examples 2 to 6, even one item among “brightness”, “color”, and “roll” is excellent. Those that were out were judged as "excellent".

As shown in Table 1, the survival rate of mother shells in Examples 2 to 6 is 29 to 43%, which is lower than 60% in Comparative Example 1, and the pearl recovery rate is also 17 to 38% and Comparative Example. The value was lower than 55% of 1. This seems to be due to the fact that the optimum aquaculture conditions have not been ascertained in pearl aquaculture which uses anticorrosion-treated magnet pieces as the core, as opposed to pearl aquaculture which has been proven for 100 years.
In Example 2 in which a nickel-plated neodymium magnet piece was cultured as a nucleus, the survival rate of mother shells was low, and the proportion of defective products was also high in quality. It is difficult to suppress the occurrence of rust only by nickel plating, and it is considered that the eluted metal ions adversely affect the mother shellfish. Poor quality was also due to discoloration of the nucleus.
In Example 3 having a core of magnet pieces coated with an acrylic resin on the surface of a plated neodymium magnet as a core, the problems of core discoloration and mother shell survival rate observed in Example 2 are improved, and mother shell survival rate Improved the pearl recovery from 17 to 23% from 29 to 31%. The percentage of "excellent" in pearl bead quality increased. This is because when the color change of the plated metal is suppressed, the metallic luster is maintained, and this can be seen through the nacre, thus giving a feeling of grace.

In Example 4 in which a polyethylene-coated magnet piece was used as a core, the recovery rate of pearl beads was not improved although the survival rate of mother shells was improved. It is considered that because the surface of the polyethylene was flat and there was no catching, many core detachment from the mother shell occurred. This is also supported by the large number of defective products in which the nacreous layer was not properly formed on the surface of polyethylene.
Example 5 which used as a core the magnet piece which further coated the surface of the neodymium magnet piece which coated polyethylene with polyethylene glycol as the core improved mother pearl survival rate to 42%, and pearl recovery improved to 38%. This is considered to be due to the fact that the affinity with the mother shellfish is improved because polyethylene glycol is hydrophilic.
Example 6 in which the surface of a polyethylene-coated neodymium magnet piece was cored with a magnet piece coated with a vinyl chloride resin containing a filler of calcium carbonate was 43%, and the mother shell survival rate was as high as 43%. Remained at 34%. Since calcium carbonate is a component of the shell, it is considered that the mother shellfish can not easily recognize the nucleus as a foreign substance. Example 6 had the highest proportion of "excellent" in quality evaluation. This is because the transparency is improved by blending a calcium carbonate filler into the resin, and a pearlescent bead having a sense of transparency is produced.

[Example 7: Through hole processing and magnetization]
The pearl beads rated as “excellent” to “good” in Examples 2 to 6 were provided with holes penetrating the magnet pieces and the nacreous layer at the center of the pearl beads by drilling. The pearl ball finished with through hole processing was magnetized in a magnetizing coil connected to a capacitor type magnetizing power supply. When magnetizing, the pearl ball in which the through hole was formed was installed so that the diameter of the magnetizing coil matched the through hole, and a current of 10,000 amperes was instantaneously supplied to the magnetizing coil. When pearl beads are regarded as the earth by this magnetization, N poles and S poles are formed at positions corresponding to the north pole and the south pole at the positions where the through holes are on the equator of the pearl balls.
In the magnetized pearl ball, a stainless steel wire having magnetism was passed through the through hole, and the design of the pearl ball having magnetic force was considered. A pearlescent ball having magnetic force through which a magnetic stainless steel wire is passed has an innovative ability to hold the pearlescent ball at any position of the wire.

Claims (13)

1. After inserting an unmagnetized magnet piece with anti-corrosion measures into the inside of the pearl shell,
   The nacre is grown around the magnet piece as a core,
   A method for producing a pearl ball, which comprises magnetizing a magnet piece covered with a nacre from the pearl shell after taking it out.
2. The method for producing a pearl ball according to claim 1, wherein the anticorrosion measure applied to the magnet piece is plating or resin coating.
3. The pearl ball according to claim 2, wherein the plating is one or more selected from electroplating, chromium plating, electroless plating, hot-dip plating, vacuum evaporation, insoluble anode and electroforming. Method.
4. The method for producing a pearl ball according to claim 2, wherein the anticorrosion measure is a resin coating, and a surface of the resin-coated magnet piece is further coated with a synthetic resin containing calcium carbonate.
5. The method for producing a pearl ball according to any one of claims 1 to 4, wherein after the growth of the nacreous layer, drilling is performed so as to penetrate the nacreous layer and the magnet piece.
6. Magnet pieces with anti-corrosion measures,
   A nacre formed around the magnet piece as a core;
   A pearl ball characterized by consisting of
7. The pearl ball according to claim 6, wherein the magnet piece is a kind selected from the group consisting of a ferrite magnet, a samarium cobalt magnet, and a neodymium magnet.
8. The anticorrosion measure is plating, and the plated metal is at least one selected from the group consisting of gold, silver, copper, platinum, tin, chromium, nickel, and alloys thereof. The pearl ball of claim 6 or 7.
9. 9. The pearl ball according to claim 8, wherein a resin is further coated around the metal-plated magnet piece.
10. The pearl ball according to claim 6, wherein the anticorrosion measure is a resin coating, and the magnet piece is coated with a resin at its periphery.
11. The pearl ball according to claim 10, wherein the surface of the magnet piece coated with the resin is further coated with another type of resin.
12. The pearl ball according to claim 10, wherein the surface of the magnet piece coated with the resin is further coated with a resin containing calcium carbonate.
13. The pearl ball according to any one of claims 6 to 12, wherein the magnet piece in which the nacreous layer is formed has a hole penetrating the nacreous layer and the magnet piece.