- Recorded Session from May 18, 2020
- Level: INTERMEDIATE
- Length: 1h 46m
Considering the occurrence of undisclosed lab-grown diamonds, vigilance combined with the use of standard and advanced gemmological tools are critical to ensure confidence in the supply line. While well-equipped labs can identify such non-natural origin and issue a report accordingly, diamond dealers, gemmologists, appraisers and retailers need instruments that help them to screen natural and some cases identify lab-grown diamonds. There are an increasing number of detection instruments and machines on the market that use different methods for screening/detection, notably:
- transparency to SW UV light
- characteristic fluorescent/phosphorescent reaction to LWUV, SWUV and other UV light
- Vis, PL, Raman, FTIR and fluorescence spectroscopy
- fluorescence imaging and other undisclosed techniques
30 loose /mounted items (which included 55 diamonds and 7 imitations) were tested in March 2020 in Vancouver with 7 instruments: the suite comprised 17 natural diamonds with natural colour (16 near colourless, 1 coloured), 4 natural diamonds with treated colour (2 near-colourless, 2 coloured), 18 HPHT-grown diamonds (16 near colourless, 2 coloured), 16 CVD-grown diamonds (12 near colourless, 4 coloured) and 7 diamond imitations (3 near colourless CZ, 3 near colourless& 1 coloured moissanite).
The samples were tested with 7 portable instruments under US$9,000.
Each member of the trade has specific needs on the type of item to be tested (loose or mounted, size and colours), the number of items needed to be tested per hour and the accepted tolerance on accuracy, as well as budget.
It is advised that a potential buyer spend at least 1 day at a trade workshop or online webinar seeing the use of standard and advanced portable instruments with samples of lab-grown diamonds before deciding which instrument to buy.
Display and demo of 5 portable instruments under US$9,000: portable polariscopes, PL/Jewellery Inspector, Synthetic Diamond Screener II, Gempen and EXA/J-screen at CGL Canadian gemlab.