Host: The Gemmological Society of Japan
Penguin's wing oyster (scientific name: Pteria penguin 〈Röding,1798〉 ), which belongs to the Pteriidae family, is one of the mother shells of half-shaped pearls used as a material for jewelry. Currently, Penguin's wing oyster produces not only half-shaped pearls but also nucleated pearls (perfect circles), and diversity can be seen as a commercial material. As a by-product of aquaculture, these mussels sometimes produce sparsely sized and baroque-shaped nuclear-free pearls. These are conventionally called Keshi pearls in the Japanese pearl industry. The problem is that it is difficult to distinguish them from Keshi pearls produced from other mother shellfish because they have a variety of appearances in terms of size, shape, and color tone. In this study, we introduce the Keshi pearls produced from these Penguin's wing oyster and also report on the search for a method of distinguishing them from Keshi pearls produced from other mother shellfish.