Pearls are formed in a number of species of molluscs viz., the pearl oysters,
window-pane oysters, edible oysters, fresh-water mussels, abalones, chanks,
topshells, turban shells etc. Pearls formed in some of the pearl oyster species are
valued very highly as gems because of their excellent shape, quality and lustre.
Pearl oysters enjoy a world-wide distribution occuring in almost all the seas of
the tropical belt. Six species of pearl oysters are known from the Indian coasts
viz. Pinctada fucata (Gould), P. margaritifera (Linnaeus), P. chemnitzii (Philippi),
P. sugillata {Ree\e), P. anomioides (Reeve) and P. atropurpurea (Dunker). Of
those, P. fucata which occurs in extensive beds in the Gulf of Mannar and to a
much less extent in the Gulf of Kutch is commercially very important being the
source of the 'Oriental pearls' or 'Lingah' pearls of great renown. P. fucata
occurring in the Persian Gulf and off the coasts of Ceylon also supports excellent
fisheries for natural pearls. The Indian pearl fisheries have been famous since
ancient times for the most beautiful pearls they yield. The other five species of
pearl oysters on the Indian coasts arc not of any importance as their pearl yield
is low or the pearls produced by them are not of high quality
