Black opals are found in Australia. This type of pearl must be cut off the shell, and is therefore hemispherical. Because of their shape, blister pearls are mostly used for earrings. Bloodstone is porous and relatively soft. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419.
Blue gold is gold with a bluish tinge.
It has been alloyed with a mix that includes iron. Bog-oak was carved and used as inexpensive Victorian era jewelry. It was also used for decorative objects, bowls, chests, dagger handles, and other decorative items. A Bohemian ruby is actually a garnet. BOKE Boke is a Japanese term for coral that is rose colored.