Minerals and Metals in Ancient India v2.c43.s3.t13.2

v2.c43.s3.t13.2

Thin alternate laminated layers of aragonite and conchiolin result in the gem of various sizes, specific gravity 2.65-2.68 and hardness around four in the Moh’s scale. Light penetrates the first few translucent layers and then get reflected; the combined reflection causes the play of colour and what we know as ‘pearly lustre’. Thinner the calcareous laminae, the more beautiful is the lustre. The pearls produced by the marine molluscs are far superior to those produced by the fresh water species.