(via ICA Early Warning Flash, no.22, March 27, 1992) Grahame Brown writes:
Background
Following the discovery of alluvial ruby in Vietnam in the late 80s, small parcels of distinctively colored purplish pink to purplish red rough, as well as some cut stones, became available for purchase in Australia in early 1990. Initially the major sellers of this ruby appeared to be Vietnamese residents of Australia. Subsequently, Australian gem merchants purchased parcels of Vietnamese ruby, in Bangkok, for resale in Australia.
Over the last year I have been requested to examine several parcels of Vietnamese ruby rough, as well as some small parcels of faceted Vietnamese ruby, to establish the natural origin of this ruby. This alert has been issued in response to my findings.
Observed features
The rough examined appeared to be water worn, and sometimes displayed visually convincing evidence of external crystal forms, and parting planes. The few unabraded fracture surfaces and parting planes on the surface of this rough allowed very limited visual access to its interior.
Suspicious were immediately raised when some of the rubies, faceted from allegedly Vietnamese ruby rough, displayed:
- diffused curved color banding
- curving empty surface reaching fractures
- profiled gas bubbles and closely associated whitish granular masses
Of these inclusions, the curved color banding was most difficult to detect. Visibility of this curved color banding was enhanced when the immersed ruby was rotated in diffused transmitted light generated from a laterally directed fibre optic wand.
As diffused curved color banding and curving surface reaching fractures characterize heat treated Verneuil synthetic ruby, and profiled bubbles and whitish granular partly melted alumina powder are not uncommonly found in the sintered area of attachment between the Verneuil boule and the ceramic pedestal of the chalumeau……a hypothesis that some parcels of Vietnamese ruby rough were being salted with rough shaped, tumbled, heat treated Verneuil synthetic ruby seems possible.
As some of these inclusions were also observed in small parcels of faceted Vietnamese ruby, buyers of this new exciting should exercise caution.
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