The trace minerals, fractures, and other imperfections that contribute to the unique fingerprint of a gemstone. All but the rarest gemstones contain inclusions, which are created during the gemstones' formation in the earth.
A naturally occurring flaw, (feather, fracture, fissure, carbon spot, or cloud), within a diamond or other stone. The test for clarity looks for these flaws.
Any substance visible within a gemstone, including fragments of a gemstone itself or tiny crystals. These entrapped "prisoners" influence value, which may be more or less depending on their number and size. If not too centrally situated, it may be possible, in cutting, to remove them from a rough stone. Cuts designed to rid a stone of inclusions generally involve considerable loss of carat weight.