corundum, ruby, Vietnam.12, synthetic corundum.7, assembled stones, gems

Investigates fraudulent ruby and sapphire marketed as Vietnamese material following the emergence of commercial production at Luc Yen and Quy Chau and the arrival of such stones in Australia from mid-1990. A collection assembled over twelve months from parcels purchased in Vietnam or Bangkok revealed numerous methods of mixing synthetic material with natural rough and faceted stones. The principal substitutes were Verneuil synthetic ruby and sapphire subjected to heating, deliberate fracture induction, tumbling, or combinations of these processes to imitate natural appearance. Faceted specimens were comparatively easy to identify through curved colour banding, occasional rounded or elongated gas bubbles, and dark, surface-reaching fractures. Synthetic blue sapphires also lacked the 450 nm absorption characteristic of the natural material considered. Manufactured ruby crystals were shaped and incised to simulate natural crystal faces and growth striations, but some displayed inappropriate bipyramidal habits, painted blue terminations, or patches of partly fused, bubble-bearing alumina. Polished windows exposed internal curved colour banding and other evidence of flame-fusion origin. More elaborate constructions included a natural, low-quality ruby crystal incorporating synthetic ruby fragments and synthetic rough with drilled cores or saw cuts filled with fused blue sapphire fragments. These additions simulated natural blue zoning, with glassy coatings sometimes concealing the openings. Other deceptive modifications included colourless oil or wax in fractures, blue dye impregnation, blue wax in surface depressions, and dark red nail polish applied to natural pink sapphire. Tumbled rough presented the greatest identification difficulty because its abraded surface obstructed microscopic inspection. Even after windows were polished, inclusion-free pieces could remain inconclusive without laboratory methods such as energy-dispersive X-ray fluorescence, examination for Sandmeier–Plato twinning, or short-wave ultraviolet immersion photography. The authors note practical limitations: twinning examination could require parallel polished windows and immersion between crossed polars, while ultraviolet photography required darkroom facilities and primarily distinguished iron-poor from iron-bearing material. A comparative inclusion list outlines features supporting natural Vietnamese origin, while recognising substantial similarities with Myanmar ruby. The investigation demonstrates that basic gemmological properties and attractive natural-looking surfaces cannot establish authenticity, especially for rough. Brown and Beattie call for guarantees from authorised suppliers, sanctions against deliberately adulterating parcels, and widespread publication of identification methods. They argue that urgent action is necessary to protect buyers and the reputation of Vietnam’s developing ruby and sapphire industry, since reliable testing of the most deceptive rough was unavailable on the mining fields.