Feature Gems & Gemology, Summer 1993, Vol. 29, No. 2

Flux-Grown Synthetic Red and Blue Spinels from Russia

Examination of red and blue samples of a relatively new flux synthetic spinel from Russia established criteria by which they can be separated from their natural counterparts. The flux synthetic blue spinels can be recognized on the basis of their inclusions, ultraviolet luminescence, and visible absorption spectrum.  Magnification is sufficient to identify the flux synthetic red spinels when flux or metallic inclusions are present; in the absence of such inclusions, however, chemical analysis is required. Red and blue natural spinels both contain significantly more zinc than their flux synthetic counterparts. Also, trace amounts of Pb (from the flux) and Pt and Ir (from the crucible) were found in some of the flux synthetic spinels.