The Application of Differential Interference Contrast Microscopy to Gemmology

Episcopic (reflected light) differential interference contrast (DIC) microscopy can reveal information about rough or cut gems that would otherwise be difficult to obtain using standard gemmological optical microscope illumination techniques. Although not widely used in gemmology due to the current expense of the specialized equipment and its limited applications, this type of contrast-enhancing optical microscopy is particularly useful for observing surface features that may help with such tasks as identifying rough gem materials, detecting heat treatment (in stones that have not been repolished) and assessing whether a gemstone was damaged after it was polished. DIC microscopy is valuable for yielding technical information about a gem, as well as for producing informative and often striking images. (C) 2015 The Gemmological Association of Great Britain