Conch pearls are not technically pearls from the gemmological standpoint, but because of their shape and colour and the fact that they come from a mollusc, they are known as "pearls".
They are produced by the conch (strombus gigas) in the West Indies, particularly in the waters around the Bahamas. The pearls are normally found in the flesh of the molluscs and the yield is very small. One would have to open several thousand shells to obtain one reasonable pearl. Even then, one would be lucky to find one of the favoured deep pink colour with the all important "flame" appearance. They are also found in yellow, white and red. The two pearls in this Art Deco brooch are particularly large and of a fine pink colour.