Akoya pearl is a type of seawater cultured pearl from the Akoya Oyster (Pinctada Fucata Martensii). Their shell can grow up to a length of 6 to 7cm, height of 2.5 to 3cm. Most of them are usually grown in the the Seto Inland Sea in Mie, Kumamoto, and Ehime prefectures in Japan. The luster of Akoya pearl is unmatched and beautiful, in which it is given the name of "Little Light Bulb". It has the ability to showcase the charm and feminine of the wearer.

Color

Akoya pearls are primarily categorized into three color ranges: white, silver-blue, and a small quantity of champagne. White pearls have the highest production volume, followed by silver-blue, and golden pearls have the lowest production. Within the main color ranges, there are also overtones, which refer to the colors found in the center of the pearls. These overtones include pink, green, and blue. By combining different main colors with overtones, Akoya pearls can display a variety of colors. The term "Tennyo" often heard, refers to white pearls that exhibit all three overtones.

Approximately 95% of Akoya pearls undergo color enhancement, to some extent, in order to meet market demand. The purpose of color enhancement is to remove organic color centers and impurities, allowing the pearls to regain their natural radiance. It's important to note that color enhancement is not dyeing; it is a widely recognized and accepted processing technique in the Japanese pearl industry and market. Color-enhanced pearls will have a slight pinkish hue, resulting in more uniform coloration and easier color matching. Pearls without color enhancement will have a significant amount of impurities and residual pigments on the surface, and their main color will tend towards yellow or cream, with a small portion leaning towards white. The Pearl Research Laboratory of Japan particularly appreciates and certifies pearls that have not undergone color enhancement. Among the non-enhanced Akoya pearls, those with the strongest luster are awarded the special title of "Matsurika" and are accompanied by a certificate. Within the non-enhanced pearl category, the highest grade is designated as "Snow White Pearl" by the Pearl Research Laboratory.

Luster

The luster of pearls, also known as "テリ" (TERI) in the Japanese pearl industry, refers to their surface brilliance. The luster of Akoya pearls comes from the high-quality calcium crystalline layers that cover their surface. When light shines on the pearls, it causes surface reflection and refraction within the layers of the pearls. The more orderly the arrangement of the pearl layers, the greater the refraction of light and the better the luster. Conversely, if the layers of the pearls are not well-aligned, the refraction of light is scattered, resulting in a relatively weaker luster.

Due to the meticulous cultivation techniques and specific temperature differences in Japanese seawater, the surface calcium crystalline layers of Akoya pearls are tightly and uniformly arranged. This enhances their luster and makes their iridescence particularly prominent. Akoya pearls with strong luster can still exhibit a bright glow even in dim lighting, as they reflect even the faintest light. This is why they are often referred to as "little light bulbs" for their luminous beauty.

Pearl Layer

The thickness of the pearl layer, known as "Maki". It is the most crucial factor when selecting pearls.

This is because the thickness of the pearl layer directly impacts the pearl's luster and its long-term preservation.

About the structure of Akoya pearls

Akoya pearls have a structure consisting of calcium carbonate crystals arranged like bricks, with a protein called "conchiolin" acting as glue between the crystals, binding them together to form the layers. Each layer is approximately 0.4μ (micrometers) thick. For instance, a 0.6mm Akoya pearl would consist of thousands of layers of calcium carbonate crystals and conchiolin.

Sea water Akoya pearls are natural organic materials that undergo certain changes over time. For example, they may become yellowed or experience peeling of the pearl layer due to aging. Generally speaking, the thicker the pearl layer, the more resistant it is to these changes over time. When the pearl layer reaches a certain thickness, the rate of yellowing due to aging tends to slow down. Conversely, if the pearl layer is too thin (0.2mm), the yellowing phenomenon may occur quickly and there is a higher risk of peeling of the pearl layer.

Strict Grading System

Akoya pearls have a official grading system that categorizes them into three grades based on their quality: Regular, Hanadama, Tennyo. Hanadama Pearl are considered the highest quality Japanese Akoya pearls. The term "Hana" in Japanese means "excellence" or "first," and achieving the "Hana" grade signifies minimal flaws, perfectly round shape, vibrant luster, and color, with a nacre layer thickness of over 0.4mm. 
Tennyo pearls, on the other hand, are the top-grade among Hanadama Pearl. Only Hanadama pearls that meet the strict criteria set by authoritative jewelry appraisal certificates in Japan are awarded the prestigious title of "Tennyo," making them exceptionally rare and valuable.

Akoya pearls are considered precious and valuable due to several factors. Firstly, the production of Akoya pearls is limited as they require specific conditions for cultivation, unlike freshwater pearls, which can produce 20-30 pearls in one cycle. Akoya pearls grow at a slower pace, with only one pearl produced per oyster's lifetime. This significant difference in quality and production volume contributes to the rarity and higher value of Akoya pearls, making them sought after for collection and investment purposes.

In terms of surface quality, common small imperfections found in Akoya pearls include pinpricks, small bumps, and surface growth lines. Completely flawless pearls are extremely rare, and therefore, the highest-quality Akoya pearls, known as Tennyo pearls, are often sold as individual loose pearls rather than being made into necklaces. As a result, the value of a single Akoya pearl suitable for necklace production may be slightly lower than that of a loose pearl.

There is a misconception among consumers that untreated, naturally colored pearls are superior. However, this is not necessarily the case. Untreated pearls do not always indicate better quality, and treated pearls do not necessarily imply lower quality. In fact, in the market, a pink-toned treated Tennyo pearl often commands a higher price compared to an untreated pearl with a yellowish hue. The reason for treating pearls is to enhance their color while maintaining or even improving their overall quality. The majority of Akoya pearls in the market are treated, and their value is determined by their attractiveness to buyers.

In summary, the value of Akoya pearls should not solely be based on their natural characteristics but also on the enhancement of their color through treatment. This does not impact the quality or lifespan of the pearls. Therefore, treated Akoya pearls can have even higher value than their untreated counterparts.

Tennyo Certificate

To obtain a Tennyo certificate issued by the Japan Pearl Science Laboratory, one must pass through rigorous scrutiny. "Tennyo" represents the cream of the crop in the white Akoya pearl category. It traces back to 2001 when the director of the Japan Pearl Science Laboratory, Hiroshi Komatsu, discovered, through observation using specialized pearl assessment instruments, the occurrence of three interference colors known as the "aurora effect" in high-quality Akoya pearls. Only Akoya pearls with a diameter of 6mm or more and possessing the "aurora effect" are given the name "Aurora Tennyo" or simply "Tennyo."
Some deceptive merchants may mislead buyers by claiming that "Aurora Tennyo" and "Tennyo" are two different grades. The truth is that the full name designated by the scientific research institute is "Aurora Tennyo," and the term "Aurora" is used in the certificate's title column, referring to the Japanese word for "オーロラ." Therefore, there is no distinction between "Aurora Tennyo" and "Regular Tennyo."
Furthermore, the standard for the pearl layer of Tennyo pearls is set at 0.4mm, and anything below that cannot be classified as Tennyo. However, there are sellers who claim that the thicker the pearl layer, the more beautiful the pearl's luster. But is this really the case? Clearly, it is not. In fact, the thickness of the pearl layer is not directly related to the pearl's luster or imperfections. The luster of a pearl is determined by the smooth and tight arrangement of the crystalline layers within the pearl's nacre, similar to laying tiles on the ground. Only when each tile is laid smoothly and tightly can a flat surface be achieved.

Matsuda Certificate

In the silver-blue Akoya pearl category, only the top 3%-5% of pearls with the best quality are eligible to be called "Matsuda." This is the special designation given by the Japan Pearl Science Laboratory to the highest-rated silver-blue Akoya pearls, and it is directly indicated as "Matsuda" on the certificate issued by the laboratory. Matsuda is a term used in the "Manyoshu," an ancient Japanese poetry anthology, to praise pearls. It means preserving the original appearance of pearls as they are retrieved from the sea, without any artificial treatment, specifically referring to blue-colored pearls.

The dreamy silver-grey-blue color of Matsuda pearls gives a sense of mystery and intellectuality, making them very suitable for modern women. The blue color in Matsuda pearls is caused by the presence of organic substances within the pearl. Moreover, high-quality Matsuda pearls have a rich iridescence that is not found in other color variations of Akoya pearls. When observed under natural light, they exhibit various accompanying colors such as pink, blue, and green. With changes in lighting and viewing angles, a strand of Matsuda pearls gradually displays a shimmering rainbow-like variation, which is captivating and beyond description using mere words or images.

Additionally, Matsuda pearls possess an extremely strong mirror-like luster that reflects one's facial features clearly. The luster of pearls is not only related to the pearl layer but also to the thickness of each layer's mirror surface. When magnified, the cross-section of any pearl resembles the annual rings of a tree, with each ring representing a layer. Generally, the more layers there are, the thinner the thickness of each crystalline surface, resulting in a stronger luster. Therefore, the Japan Pearl Science Laboratory has set a requirement for Matsuda pearls to have a pearl thickness greater than 0.6mm, highlighting their uniqueness and rarity.

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