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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

Description of inclusion features have been provided by Peter G. Read

601Regency synthetic Emerald

This synthetic emerald is grown using the original Linde technique and Union Carbide patents. Constants are generally close to those of the natural stone, although the S.G. is slightly lower, at 2.68. There's very little iron content, with the result that the stones have a high S.W. U-V transmission factor and a strong red fluorescence (even under a beam of high-intensity white light).

Typical inclusions are wedge-shaped, dagger-like growth tubes, two-phase features stemming from phenakite crystals, and the occasional healed-crack type of feature.

602Synthetic Russian Emerald

603Chatham synthetic Emerald

604Synthetic hydrothermal Emerald

Characteristic inclusions include two-phase feathers, nail-like microscopic crystals, and elongated flowing growth features. The stones may also contain small lengths of tubular two-phase inclusions (probably growth tubes).

605Emerald, natural, Brazil

606Lennix synthetic Emerald, (flux-fusion)

Developed by M. Lens of France, these synthetic emeralds are grown as rectangular rather than hexagonal crystals and have a tabular habit. Their constants are slightly lower than those of the natural stone (R.1.=1.562, 1.566; D.R.= 0.004; S.G.=2.62-2.65).

Two-phase and three-phase inclusions resembling feathers and particles of flux are typical, as are spiky cavities. The most characteristic features are small crystal clusters looking like rosettes. The stones show a strong red through the Chelsea filter.

607Quartz, green, dyed