Akoya 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

Akoya Pearls

Akoya Pearls Originated from Japan

Akoya pearls, also commonly known as Japanese pearls, are pearls from the akoya oyster (scientific name: Pinctada fucata martensii) native to Japan.

Akoya oysters are smaller in size than black lipped and White lipped oysters, and the size or akoya pearls are also smaller when compared, about 6 to 7 mm in diameter, and the largest pearls are about 12 mm.

*Black lipped oyster and black lipped pearls (left) Akoya oyster and akoya pearl (right)

The noteworthy feature of akoya pearls is that each layer of nacre that determines the pearl’s luster is very thin and dense compared to other pearls. The delicate and transparent pearl layers create highly reflective luster, and their elegant brilliance and soft colors are loved by women from all over the world including women in Japan.

Production Areas of Akoya Pearls

In the past, before pearl farming even started, many beautiful pearls were collected in Japan because the four seasons of Japan with each season having very different temperatures and climates were very compatible for akoya oysters to grow. The moderate underwater temperature change brought by each season and the rich nutrition carried by the Japan Current and Tsushima current provided a good stimulus to the biocycle of akoya oysters, resulting in formation of pearls with a fine and firm quality of nacre.

Outside of Japan, akoya pearls are mainly produced in Vietnam. Vietnamese akoya pearls are produced by exporting aakoya oysters from Japan. In Japan, pearls are cultured mainly in western Japan, including Mie prefecture, one of Japan’s most famous pearl growing prefectures.

<Main production areas in western Japan>
1. Mie Prefecture: Shinmei, Katada, Fuseda, Funakoshi
2. Ehime Prefecture: Yusu, Kitanada
3. Fukuoka Prefecture: Ainoshima
4. Saga Prefecture: Karatsu
5. Oita Prefecture
6. Kumamoto Prefecture: Amakusa
7. Nagasaki Prefecture: Tsushima & Iki

The pearls hold unique characteristics depending on the farm. For example, farms in Yusu and Kitanada in Ehime Prefecture produce large pearls stably, while the farms in Katada, Fuseda and Funakoshi in Mie Prefecture mainly produce small pearls of 4 mm or smaler, called “Rin-dama”. The farms in Tsushima and Iki in Nagasaki Prefecture are also famous for winning multiple awards, including the Emperor’s Prize.

Stepping aside from pearls, many people think of tuna when it comes to feasting on an expensive fish in eastern Japanese region. In western Japan, people think of sea bream instead. Fukuoka prefecture has one of the largest catch of sea breams in Japan and the red sea bream farms in Naruto Strait, Akashi Strait and Uwajima are well known. Akoya oysters and sea breams, which are farmed mainly in western Japan, may have a lot in common with their habitat conditions.

What Colors are Akoya Pearls?

The Akoya pearls displayed on the store windows are mostly white. Natural akoya pearls however, each have very unique colors and there will never be a pearl with the same hue. Akoya pearls are classified into seven color types: pink, silver, cream, gold, green, blue, and and even black. Akoya pearls offers a wide range of colors. Nevertheless, white pearls are always the most popular perhaps due to the strong image of pearls to have “white color and round shape”.

*Akoya pearls at the time of harvest

*White akoya pearls with pink interference color

History of Akoya Pearls

Akoya pearls has a long history in Japan. According to Gishi-Wajin-Den, from the beginning of the Zhengshi era, in year 247 to 248, when Jin dynasty united three countries of Wei, Wu, and Shu. The Queen of Wakoku, or known today as Japan, Iyo sent envoys to Jin dynasty with 5,000 white beads, two blue magadama as gifts as well as 30 male and female slaves. At that time, Japan was in the Kofun period, and white beads are speculated to be white pearls, and blue magadama are considered to be large jade beads. Japan is an island country rich in marine resources, and this historical writing shows that pearls, which are gems from the ocean, have been valued since the ancient times.

Also, there is an interesting episode of Kokichi Mikimoto, the founder of MIKIMOTO. When he had the chance to meet the Emperor of Meiji, Mr. Mikimoto said, “I’m going to put pearl necklaces on every woman’s neck all around the world.” Now women around the world enjoy the elegance and beauty of Aakoya pearls originated in Japan and wear them with different outfits. Kokichi Mikimoto’s passion for pearls, his dedication and his efforts have created the exact world he once dreamt to see.

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