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HRD Detects Topaz Imitating Diamonds

Jul 16, 2017 8:48 AM   By Rapaport News
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HRD Antwerp has identified two stones that were believed to be diamonds as topaz, reflecting a trend to fool rough diamond buyers with the cheaper gemstone.

The two large, near-colorless rough stones, weighing 50.08 carats and 38.18 carats, were submitted recently to HRD’s research department to determine their quality, the diamond laboratory said last week. Investigation of the growth lines of the stones revealed them to be topaz, a silicate mineral of aluminium and fluorine, rather than diamonds.

Topaz is a colorless diamond simulant, with a similar density to a diamond, that can easily be misidentified. The market value of topaz, measured in US dollars per carat, is far below that of rough diamonds.

Topaz and diamonds display very different growth lines and growth structures due to their particular crystallization. A Raman analysis, used to provide a structural fingerprint by which molecules can be identified, clearly indicated that the heavily included stones were topaz and not diamond. A detailed study of the large inclusions also showed the presence of typical inclusions of topaz that are not generally found in diamonds.

“It seems obvious that the topaz crystals were manipulated and polished to show the typical growth lines and growth structures of diamonds to fool any potential buyer,” HRD said.

“The value of this quality of colorless topaz is believed to be not more than $5 per carat worldwide. More and more topaz [stones] are cut to fool rough diamond buyers,” the laboratory added.

According to the Gemological Institute of America (GIA), topaz is one of many near-colorless diamond simulant materials that may be faceted to bear a closer resemblance to a diamond.
Tags: diamond imitations, Gemological Institute of America, gemstones, GIA, HRD, HRD Antwerp, Laboratories, Rapaport News, Rough Diamonds, Topaz
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