Other Pearls

Pearl foundation

History of Pearls

Pearls are an incredibly unique gemstones. While most precious gems are formed in the ground, surrounded by rocks, pearls are the gemstones created inside of a living creature. Pearls are therefore sometimes called bio minerals.

Pearls have been revered since approximately five thousand years ago in all over the world, for its natural glistening beauty placed onto oyster beds.

A Chinese philosopher, Confucius wrote in his book “Book of Documents” that fresh water pearls were presented as gifts to Chinese royalty as early as 2,206 BC (4,186 years ago). While in Europe, from ancient Rome, pearls are often quoted in bible verses. For instance, in the New Testament, the verse states as " Again, the kingdom of heaven is like a merchant in search of fine pearls. When he found one very precious pearl, he went away and sold all he had and bought it” (From The New Testament, Matthew). Pearls have been known as the “Queen of Gems”, and pearls have been coveted for centuries in the form of jewellery.

Before cultured pearls were introduced, the only way of collecting pearls was through diving to retrieve the pearl oysters. Pearl jewellery therefore, was considered the ultimate status symbol for royalty and the ruling class for being the rarest gems.1

*Portraits of royalty and authorities with pearls

Today, pearls are named as five precious stones along with diamonds, rubies, sapphires, and emeralds. Pearls have long been worn by women, and in modern age, pearls are used not only in formal occasions but also worn with casual, everyday clothes, gaining popularity among women. The origin of the diversification of pearl jewellery generally dates back to the first half of the twentieth century, when Coco Chanel launched her collection incorporating imitation pearls. Coco Chanel was a sensational pioneer in teaming her pearls with casual daywear. 2

Definition of Pearls

“Imitation pearls” have grown popular lately and you might have often heard about them. Some faux pearls, such as cotton pearls, the difference can be seen at a glance when compared to genuine pearls (stated as "pearls" for convenience here). The differences between imitation pearls and pearls are their price, weight, texture, and the most notable difference is how they are manufactured. The definition of pearls determined by the pearl trading market is introduced here.

Pearls are defined as “metabolites produced by living oyster that can form nacre, and their visible components are the same as the mother of pearl which has bright and clear nacre inside the shell.” To qualify as pearls, first, pearls must be formed in a “living shell” with bright and clear pearlescent inside shells, like abalone, oysters, black lipped oysters and White lipped oysters. Second, the shining part of the inside shell called “nacre” must form layers around pearls covering the whole gem.

*Inside of black lipped oyster and black lipped pearls

How Nacre Works

Pearls are formed when nacre, the same component found on the external surface of a pearl and the internal lining of shells, forms layer upon layer of this coating. As a defense mechanism, nacre is used to coat the irritant and layers of nacre form around the nucleus. Therefore,  when the time of mother oyster spent underwater before the pearl was harvested becomes longer, the size of pearl grow bigger. There are several other factors affecting the size of pearl such as the size and vitality of the mother oyster that produced the pearl and the size of the nucleus, but generally speaking, larger pearls spent longer time in their shells before they were harvested.

Nacre is Composed Of “Calcium Carbonate” and “Protein”

Nacre is consisted of "crystallized calcium carbonate that account for 95% of the nacre" and ""calcareous proteins called “conchiolin”". The structure of nacre resembles a brick wall at the microscopic scale: Calcium carbonate platelets ('bricks') alternate with conchiolin layers ('mortar').

While the solid platelets serve as the load bearing and reinforcing part, energy can be dissipated into the soft polymer segments. Together, nacre is composed of layers of calcium carbonate platelets and conchiolin layers arranged in a continuous parallel lamina.

*Enlarged image of surface of black lipped pearl

*Reflection of light and nacre

Since conchiolin has a low penetration of light, pearls with many conchiolin have poor luster quality and weak reflections that are quite blurred.

Therefore, the high quality nacre must be composed with minimum amount of conchiolin to penetrate the light, and nacre plate should be packed with: even shaped, no lack, maximally large calcium carbonate crystals to reflect the lights desirably. Layers produced by high quality nacre reflect more lights from the inside, resulting more luster in pearls.

* The correlation between the thickness of nacre and pearl luster Cultured for approx. 6 months (left), approx. 24 months (right)

“Luster is the Most Important Characteristics for Pearls ”

Luster is the reflection and refraction of light as it passes through layers of aragonite. The intensity of a pearl's luster can be an indicator of nacre thickness. The special shine pearls possess is called “luster”. Luster does not simply refer to pearl’s shine. According to “Pearl Dictionary” supervised by renowned Hiroshi Komatsu, luster is defined as:

"The beauty of gemstones is defined subjectively, but generally speaking, the beauty is determined based on five optical effects: cut, shape, color, transparency, and luster. The gems listed in the five precious gems also share these effects. (Omitted) Gems like ruby and sapphire can produce beautiful optical effects such as asterism (star effect). High quality pearls have a strong “luster”. The term “luster” is different from the luster of mineral based gemstones, and refers to the color with brilliance, or interference color. This is due to the interference of light, which is created by the neat stacking of the nacre. This optical effect is probably the biggest reason why pearls are praised as beautiful gems. 』3

Black lipped pearls have a famous color called "peacock color" with a green rim and a red overtone. This is formed by the overlapping of colors, created by the pigments contained in one layer of nacre reflected with light and stacked in multiple layers. The pearl with this beautiful interference color-"luster" has a very high quality of nacre, which proves to be a durable, long-lasting and good quality pearl. This is why pearl dealers often say that “Luster is the Most Important Characteristics for Pearls”

*Famous “peacock color” of black lipped pearl

*Black lipped pearl with high luster

*Black lipped pearl with hazy luster

*Black lipped pearl with blurred luster

Pearl Grading

Pearls are graded on six criteria: Luster, nacre thickness, Surface, Flaws(Blemish), Shape and Color. The final grade is given after all six criteria have been evaluated.

LUSTER - Luster measures the rate of reflection on a pearl’s surface, and the amount of light reflected on the pearls. Luster is sometimes referred to the most important value factor when grading pearls. The overtone color and body color should look different when pearls with superior luster are held horizontally at eye level. Nacre thickness - Nacre quality refers to indentations in the nacre. For beautiful, thick layers of nacre requires dedication of pearl experts and great underwater environment. More nacre layers result in better grades. SURFACE - Pearls that feature clean surfaces without inclusions like chalky spots and wrinkles will be much more highly valued than pearls with multiple blemishes. Pearls with nacreous layer like mirrer like quality receive better grades. FLAWS(BLEMISH) - Pin-pricks are sometimes referred as pearl’s dimple. Since pearls are a product of nature however, there will always be some form of blemish such as pin holes, scratches and dents. Almost all pearls have some sort of blemish and pearls with less blemishes will be much more highly valued than pearls with multiple blemishes. SHAPE - Pearls come in multiple shapes and they each have names. As people say “Pearls are round”, some pearls come in round shape, others come in the shape of rain drop, button, Keshi, or smooth. Lately, flat pearls called flake and unevenly shaped pearls called baroque are gaining popularity. COLOR - Color of pearls depends on the color of mother oyster. Akoya pearls tend to have yellow and pale peach color and black lipped pearls have countless, multiple colors.

Pearl Processing

Pearl treatments can be roughly divided into two types: “treatments for enhancing pearl’s natural beauty(1)” and “treatments to add and create pearl’s beauty artificially(2)”

The first enhancing treatment(1) is often referred to as makeup for pearls, 1. " Pre-processing ", mainly performed in the subsequent process with the intention of facilitating the penetration of the solvent. 2. “Drilling”, For Akoya pearls, holes are drilled in the pearl for easier solvent soaking. 3. "Stain removal" , to remove impurities that have entered between the nucleus and the nacre. 4. “Bleaching”, in order to remove the color pigment found in pearl protein. 5. “Minute dyeing”, gentle dye is used with alcohol to bring out the original color of the pearl.

The second type of pearl treatment(2) is sometimes referred to as plastic surgery for pearls. This treatment uses the same processing technique of 1 to 4 above, and in addition, coloring treatments that change the color of pearls by chemical reactions such as strong dyes or silver nitrate, or coatings that protect pearls from sweat or acid, or increase the surface texture of pearls are conducted.

Most Akoya pearls currently on the market are chemically treated to enhance their natural beauty. (According to the Fisheries Agency's “Special Issue on Pearls-Fisheries” (issued in 1958), the percentage of Akoya pearls that can be used without processing is about 15%.)

Philosophy of Seibido Pearl

Seibido Pearl consider beautiful pearls to be "pearls with multiple high quality, fine and transparent nacre layers." We consider “luster” and “Nacre thickness” as our biggest value factors.

High luster is a sign of good pearls. High quality pearls do not fade or become hazy even after many years. Rather strangely, at Seibido Pearl, we have witnessed pearls with higher quality tend to gain more lustrous over time.

In addition, Seibido Pearl only offers unprocessed black lipped and White lipped pearls. Pearls have all-natural colors and have not been subjected to any chemical treatment such as toning, dyeing or even any types of pre-treatment. If processed, the delicate structure of the pearl becomes unstable, and external stimuli may cause unexpected changes in quality. We believe that high-quality pearls are naturally full of brilliant vitality and shines beautifully without being processed.

Pearls grow older with customers, and pearls should maintain the same quality as they were first harvested.

As a company passing down the story of pearls to customers, it is our mission to guarantee the quality of pearls until they reach our customers, and we have been proudly building trust with customers.

[1]『真珠』白井祥平著 海洋企画
[2] [3] 『真珠辞典 真珠、その知られざる小宇宙』小松博監修 白子修男発行 繊研新聞社

Abalone Pearls

Abalone pearls are pearls from the abalone (scientific name: Haliotis). The meat of this oyster is eaten as food. Abalone pearls are produced in Japan, the United States, Mexico, New Zealand, etc., and abalone farms are only operated in New Zealand. There are only a limited amount of cultured abalone pearls, and majority of these pearls form naturally without human intervention.

*Interior of abalone shell

*Exterior of abalone shell

Natural abalone pearls are mostly flat and have a horn-like shape. Such shapes are created because abalone shell’s nacre, which forms pearl layers around nucleus, gets damaged by small insects and debris when the abalone, which is a single-shelled mollusk, moves through rocks.

Abalone pearl farmers produce abalone pearls by gluing small dome-shaped disc made of resin to the inside of the abalone’s shell and leaving it while the animal covers the insert with iridescent nacre. At the end of the culturing process, the meat is harvested and the mabe pearls are cut out of the shell.
The reason why culturing abalone pearls is very difficult is that the well-established mabé culturing process that inserts a nucleus into the shell does not work well with abalone shells since abalone shells tend to float and move often.

Another reason is that single shelled abalone is more likely to spat the nucleus compared to bivalve like black lipped or white lipped oysters. * Please see also: Mabe Pearls

Cultured abalone pearls and wild abalone pearls differ in shapes, but the most distinctive feature is their beautiful colors. Abalone pearls in Japan and Mexico often have pale colors such as distinctive soft gray or blue. Abalone pearls from the United States and New Zealand have vivid, bright colors that resembles deep ocean. All colors are beautiful and are widely loved as rings, pendants and brooches. (Picture in bottom: dome shaped cultured abalone pearls)

*Pale colored abalone pearl

*Brightly colored abalone pearl

* After pearls are cut out of the shell, the abalone shell pieces are glued on the flat surface of the pearls

* shapes of nucleus influence shapes of pearls

※1~2 reference 
www.karipearls.com/blue-pearl.html / Kari Pearls
「Blue PearlCulturing Abalone Half Pearls」Blue pearl, the story of New Zealand Eyris Pearl

Conch Pearls

Conch pearls are produced by the queen conch (Scientific name: Strombus gigas) found mainly in the Caribbean. The queen conch is a large oyster, like a sea snail with a spiral-shaped shell, that is about 23 cm.

Culturing conch pearls is technically challenging and all conch pearls are wild pearls. Since the quality and production are not controlled by farmers, conch pearls that qualify as jewellery gems are very rare. Some suggest the probability of producing jewellery quality pearl is one out of 10,000 shells (37500 kg worth).

The rarity of conch pearls and the fact that conch pearl is non-nacreous, conch pearls are treated differently from oyster pearls. They are traded based on the size by carat weight, a unit used for measuring gemstones like diamonds instead of “momme”, a unit usually used for oyster pearls. The price for conch pearls is outstanding among pearls. For example, a conch pearl with a diameter of about 5 mm can cost USD4,500 to 5,500. Furthermore, the finest examples of conch pearl often exhibit a “flame-like structure” that’s visible to the naked eye. They are considered to be even more valuable.

There are only a few conch pearls found annually with beautiful hues of wild pearls and the brilliant luster. Conch pearls are truly miraculous pearls created for the very special wearers.

*The queen conch mollusk

* Conch pearl’s beautiful flame structure

Keshi Pearls & Baroque Pearl

Many people have the image that “pearls are round.”. In fact, true round-shaped pearls, while a major goal of pearl farmers everywhere, remain a tiny percentage of each yearly harvest. What other shapes do pearl form?

Pearls come in various shapes such as drop, button, oval (egg shaped), baroque, circle, flake, keshi, twin(snowman shaped) and more. Pearls are formed in mother oysters and their shapes, colors, and sizes vary significantly. The unique shape of the pearl is integrated in the jewellery designs without any shape modifications and is loved by many people, including designers and pearl lovers.

* “Inaho”, a brooch made with mabe keshi pearls

* “Pear” a pendant made with an oval black lipped pearl

This section further explains “keshi pearls” and “baroque pearls”.

keshi pearls

Keshi is a Japanese word that stands for “poppy”. Keshi pearls are small pearls that resemble poppy seeds, regardless of the type of pearl shells. Another important aspect of Keshi pearls grow without a nucleus.

Round pearls are formed by the technician carry out the inserting operation a round shaped nucleus and epithelial cells of the mantle into the mother oyster, and then the nacre layers create a pearl. However, Keshi pearls do not have nucleus because Keshi pearls are formed by natural accident like: peels off the epithelial cells of the mantle, or intrusion the small insect or grains of sand. Due to this, Keshi pearl have a nacre which is thick and highly lustrous.

Further, natural keshi pearls offer wide range of colors and shapes, since they are without round shaped nuclei and no farming techniques that control pearl colors have been applied. Keshi pearl’s rounded, smooth edges are widely used as a bracelet or long necklaces by connecting them, and they are also commonly used as earrings and pendant tops.

* “Bouquet” a pendant with colorful black lipped keshi pearls

* Akoya keshi pearls of various sizes

Baroque Pearls

Baroque pearls are named after a Portuguese word “baroque”. As its name suggests, they are not round shaped pearls, but have irregular shapes that cannot be categorized as buttons or drops. Baroque pearls come in every cultured pearl type like keshi pearls. In recent years, baroque pearls have been gaining popularity for their one and only, unique shapes.

*Earrings with White lipped baroque pearls

Mabe Pearls

Mabe pearls, also known as “Hankei” pearls(*hemi-spherical pearls).

The mabe oyster (Pteria penguin), which grows mabe pearls, is also commonly known as the penguin’s wing oyster, due to shell’s shape resembling an expanded penguin wing when the shell is opened. The mabe oyster is a very large mother oyster and it is about 20 -30 cm long. The main production areas of mabe pearls are Amami Oshima of Japan and the Philippines, which inhabit relatively warm water. Amami Oshima, the northernmost point of the mabe oyster habitat, is also famous for producing beautiful “Hankei” pearls.

* Mabe pearl oyster

Mabe pearls are often referred to as “Mabe pearls are “Hankei” pearls and “Hankei” pearls are mabe pearls.” The mabe oyster and mabe pearl farming technique are the reasons why mabe pearls are harvested as “Hankei” pearls.

There are two main types of pearl cultivation: “”the method of inplantation of a bead nucleus and small portion of mantle tissue called “piece” into an mother oyster’s body”” and “”The method of gluing a hemi-spherical nucleus inside the mother oyster’s shell””.

The former method is used for round pearls and the latter grows “Hankei”(*hemi-spherical pearls) pearls.

Mabe oysters have very strong adductor muscles because they live in areas with high tides. Mabe oysters have very strong adductor muscles because they live in areas with high tides. Even after the success of inserting operation, they tend to spat the nucleus or hurt themselves with their own strong muscles. Furthermore, due to the structure of the mabe oyster, inserting operation for round pearl should be cut a vital spot of mother oyster. In addition, even if the operation succeed, almost they became weak or illness. Hence, culturing round pearls out of mabe oysters was considered technically impossible, and “Hankei” pearls became the mainstream instead.

*Blistered mabe pearls

Mabe pearls have a special characteristic of having great quality of nacre, since each layer of nacre is very thin and dense even when compared to other pearls. The delicate luster and nacre have beautiful rainbow-colored interference color, which is also different from the white Akoya pearls. The beautiful color shining from the inside of the pearls leaves a unique presence and pearls are popularly used as earrings, pendants and rings.

Miraculous Round Pearl

Mabe “Hankei” pearls(*hemi-spherical pearls), generally have white hue. Round mabe pearls however, have a very deep and distinguished brown gold color that is not found in other pearl oysters.

As mentioned earlier, cultivating method for mabe “Hankei” pearls have now been established, and “Hankei” pearls are distributed stably to the market. But, There was once a pearl farm that succeeded in culturing round shaped mabe pearls, first time in the world.

Round mabe pearls were cultured in the farm in the Philippines and they naturally have the stunning brown gold color that resembles the sunset in Manila Bay. Without the technical difficulties, round mabe pearls with outstanding luster and beautiful color might have been distributed and they might have been as popular as Akoya pearls.

Unfortunately, the only pearl farming expert who had the technique of cultivating round mabe pearls has passed away, and the only existing pearls are the ones already on the market and the ones owned by Seibido Pearl. The perfectly round mabe pearls are by-product of continuous efforts and wisdom, and they teach us the true value of pearls that cannot be measured by price alone.

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