What is a seed crystal?

Seed crystals are tiny single crystals made to dissolve in a solution (or melt) from which larger crystals are drawn either by precipitation, centrifuging or drawing up from a melt. Seeds have the same chemical composition and crystalline structure as that of the larger crystal. Large crystals are grown on a preferred geometer (normally the most densely packed) plane of the seed. Such seeding is a common practice in semi-conductor industries and making artificial single crystal gemstones like silicon, germanium, sapphire, diamond, zirconia, etc.