Indian Gemological Institute – Gem Testing Laboratory, Delhi
examined a 2.74 ct colorless Natural Topaz which was polished to imitate a
rough octahedron crystal, probably to imitate diamond. Rough was beautifully
polished depicting striations parallel to octahedron edges and were made as in
to show Trigons, natural growth markings present on diamond octahedron
crystals. Crystal’s edges were also kept little rounded as common with diamond
roughs. On first instance any unexperienced person can presume it to be a
diamond. Although crystal was not able to mimic adamantine luster of diamond
and sharpness of trigons perfectly.
Under UV rough was inert. Specific gravity of rough was
3.50. Under the magnification rough showed large finger prints with big phase
inclusions, which is impossible in natural diamond due to the conditions in
which the diamond grows. Rough showed typical infrared spectra of natural
Topaz.
Rough was concluded to be a natural topaz, smart imitation
of diamond..
But not smart enough to fool FTIR.
Striations were made parallel to facet edges, which were kept little rounded. In the center of facets trigon like marking were left.
Fingerprint and phase inclusions were present in rough.
Brown color blady crystal and fibre like inclusion was also present which is generally observed in topaz.
Topaz crystal imitating diamond rough showed typical natural Topaz Infra Red Spectra.
Comments and suggestions are welcome.
(Photographs are taken by the author.)
Author:
Meenakshi Chauhan
meenakshi@gjepcindia.com
Indian Gemological Institute - Gem Testing Laboratory
Jhandewalan, Delhi
(Projest of GJEPC)
