Dichroscope

The dichroscope is an important pocket instrument used in the field of geology, and can be used to test transparent gemstones (crystals). Experienced geologists using pleochroism can successfully detect gemstones from other artificial stones using this instrument.

Calcite dichroscope

There are two types of dichroscopes available: calcite and polarizing. Of the two, calcite gives better results and is widely used by experienced gemologists. With the polarizing type, only one pleochroic color can be seen at a time. This makes the process time-consuming and difficult, though it is the most economical way to get results.

The dichroscope has been used since at least the start of the nineteenth century.^[1]

References

1. Ferguson, James; Brewster, Sir David (1823). Lectures on select subjects in mechanics, hydrostatics, hydraulics, pneumatics, optics, geography, astronomy, and dialling 2 (Third ed.). Edinburgh: Stirling & Slade, and Bell & Bradfute. pp. 333–336. Retrieved 12 November 2012.