A variety of pearl that is of an unusual natural color (other than the pink of the rosée pearl), e.g. faint tinges of blue, green, yellow, bronze, grey, brown or black. Their value is usually lessthan that of a rosée pearl of comparable size and quality. The colors, derived from the water of the source, are dependent upon the translucency of the outer skin and the character of the interiorlayers of calcite, aragonite or conchiolin, and also sometimes upon material in the absorbed water; thus, white pearls are often initially greenish until they become dry when the water has evaporated.