About Pearl Luster | Tensei Pearl
About pearl luster
The shine of a pearl is called "teri" (luster). Luster is one of the essential factors in choosing pearls. At Tensei Pearl, we cultivate koshimono (two-year) pearls with a particular focus on luster and nacre.
Comparing luster
Luster differs from pearl to pearl, and the stronger the luster, the rarer the pearl.
In the image, you can see that the luster gets better toward the right. It is hard to tell from a single pearl, but side by side the difference is clear. Simply put, the more clearly you can see the round ball-like core at the center of a pearl, the better its luster and the stronger the pearl.
The structure of a pearl
As the diagram shows, a pearl is made of many calcium carbonate crystals stacked like bricks. Between them, a protein called conchiolin acts as glue and forms the nacre.
Each layer of nacre is about 0.4μ (microns) thick, and a pearl is made of more than 1,000 of these layers.
Why pearls have luster
When light hits a pearl, it is reflected by the surface and by each layer inside the nacre. If the layers are regularly arranged, more light is reflected and the luster is better. If the layers are uneven, the light scatters and the luster is weaker.
Interference colors of pearls
When two or more light waves overlap at the same point and strengthen or weaken each other, this is called interference. In pearls it is a phenomenon called "multilayer interference", and depending on how the light hits, pink or green interference colors appear, like on a soap bubble. It is closely linked to nacre: the thicker the nacre, the stronger the interference colors.
As in the photo, a pearl with very strong luster shows a sharply defined core at its center, along with strong interference colors. The luster of a pearl can be called a fusion of the shine from reflected light and the glow from within created by the interference of light.
Why harvest timing matters
We must not forget the timing of the harvest. When snow begins to fall on Yura Peninsula, in the coldest-water season of the year, Akoya oysters that have stored nutrients form nacre with a fine crystal structure on the inside. This phenomenon, called "keshō-maki" (the finishing coat), greatly affects the finished pearl. The finishing coat makes the surface smooth and gives an even more beautiful shine.
Every year, the pearl auctions held by the fisheries cooperative begin in mid-December. Tensei Pearl does not sell at the auctions, so we can freely choose the harvest timing according to that year's water temperature. This cultivation skill, built on knowledge and many years of experience, is the foundation of Tensei Pearl.
