パール - 穴なし
Pearls are products of bivalve mollusks (mainly oysters and mussels). They are built up of nacre (mother-of-pearl), which is mainly calcium carbonate in the form of aragonite crystals, and an organic horn substance known as conchiolin that binds the microcrystals concentrically around an irritant. Although pearls are not especially hard, only about 2.5 to 4.5 on the Mohs scale, they are extraordinarily compact and very difficult to crush.
The typical pearly luster is produced by the overlapping platelets of aragonite and film of conchiolin nearest to the pearl surface. The color of pearl varies with the type of mollusk and the water, and is dependent on the color of the upper conchiolin layer. Pearls may be natural (occurring without human intervention) or cultured; and they may occur in the ocean or in freshwater.
全体の評価 -> 10
Many beautiful gems on the site. Love that you are actually shipped the gem that is shown in the photos. Also cool that they give a write up of each gem detailing hardness, characteristics, and best uses for mounting. Great site! Looking forward to seeing these gems in person.