A resurgence in the demand for fine-quality red spinels may be the catalyst for the recent appearance of flux synthetics, says the SSEF Swiss Gemmological Institute.
Several red spinels sent to the institute for testing following the Hong Kong Jewellery and Watch Fair in September turned out to be lab grown. According to the institute, the spinels have also been turning up in Bangkok in the last month.
“The investigated flux synthetic spinels are very convincing and similar in appearance to natural spinels of best quality,” the group said in their October newsletter. “Only by meticulous microscopic observation and chemical analysis, their synthetic formation may become evident. As their identification is difficult if not impossible for the normal gemstone dealer, testing of spinels by a reputed gemmological laboratory becomes an issue nowadays.”
Flux synthetic spinels show only a few inclusions, mainly jagged flux residue, metallic flakes, and small, parallel hollow channels. Natural red spinel, on the other hand, is often very included with healed fissures consisting of small octahedral negative crystals.