We have selected samples from C.I.G. 's comprehensive gem study collection which are difficult to identify. Most pictures were taken with an immersion-scope (methylene iodide or benzyl benzoate); under a common "dry" microscope with dark-field illumination many features shown here may not be visible. A detailed booklet with computer diskette containing over 100 micro-photographs is available from Gemlab Book Services . © 1996 J. W. Kuehn
Glass Doublet, with garnet top
Sapphire Doublet, glue dyed blue
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