corundum, inclusions.5, photomicrography, gems

This note deals with some gemologjcal applications for n tool well known to microscopists: the first-order red compensator. In gemological microscopy, the compensator can be useful in locating interfer-ence colors and optic figures in birefringent materials and in delipeating strain in gemstones. -Inpolarized-light photomicrography, a properly positioned com-pensator &in reduce the exposure time required and thus the risk of film reciprocity failure and of poor-quality images resulting from random vibrations of the microscope and its accessories.