An Introduction to Gem Origin and Occurrence Gems are found worldwide. When there is a sufficient quantity to be worked, it is termed a deposit. A deposit, as well as the location of discovery of a single find, is termed the gem occurrence.
Deposits can be primary or secondary in nature.
A primary deposit indicates the gem occurrence is still at the original location or at the place of formation. During this process harder gems become rounded, whereas softer gem material is destroyed or reduced in size. Most gemstones are minerals and originate from melts, solution, or vapors. The atoms arrange themselves from a disordered state into an orderly crystalline state, with growth dependent upon the availability of free space. Magmatic minerals crystallize from magma, lava, or gases and are found in igneous rock.