Any element except carbon was not detected on the tables and crown facets by chemical analysis on the diamond surface by EDXRF. On pavilion facets Si (silicon) and Au (gold) were detected other than carbon. According to the EGL report, SiC (moissanite) was allegedly detected on the pavilion. Also GIA Insider reports that alternate layer of SiO2 and metals such as Au, Ag or Al were recognised.
@@Acid-resistance test using aqua regia (nitric acid 1: hydrochloric acid 3) was performed to study resistance to acid and confirm the material of the coating layer. The stone showed no change three minutes after boiling in the aqua regia. After ten minutes boiling, no change was recognised apparently, but with a differential interference microscope removal of coating layer was easily observed. Thirty minute soaking in the fluid slightly deteriorated the pink colour of the stone, and obvious exfoliation of the coating was recognised under a gemmological microscope. Then the coating layer was totally removed by rubbing the stone strongly with a jewellery cleaning cloth. The colour grade of the stone after the rubbing was K (faint brown) (photo-7).
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Photo.7:
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Before (left) and after (right) rubbing off coating / a. face up, b. face down.
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*Coated diamonds are not graded for a grading report. On the identification report, disclosure comment gthe stone is treated by coating of artificial colouringh is noted.
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