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EGL USA announces potential "indicators" for lab-grown diamond detection
based on preliminary studies
VANCOUVER, Aug.
27 - EGL USA announced two weeks ago to the trade the recent
developments by Apollo Diamond in the production of gem-quality
Chemical Vapor Deposition (CVD) laboratory-grown diamonds, which
reportedly will be available in limited quantities late in the year
to early next year. EGL USA has been studying a small sample of
these diamonds on loan from the manufacturer.
EGL USA's Director of Canadian Operations Branko Deljanin, B.Sc.,
GG, FGA, an expert on HPHT diamonds who has spearheaded the lab's
research on CVD diamonds for the past year, says that, as with HPHT,
it requires advanced instruments to conclusively identify the high-quality
single CVD diamond. "Very low nitrogen concentration and clean stones
make them extremely difficult to identify," said Deljanin.
However, EGL USA found three early indicators that gemologists and
equipped laboratories could potentially use to screen for CVD diamonds,
based on the lab's preliminary studies of five samples. These findings
were presented this month at two Canadian jewelry trades shows in
Toronto and Edmonton.
- Fluorescence under short-wave ultraviolet
light (yellow-green) was one or two degrees stronger than under
long-wave UV.
- Most of the CVD diamonds studied
had clouds of white particles, which tended to show up in one
plane. These inclusions can show up in natural diamonds as well,
but tend to be more dispersed.
- Cathodoluminescence colors (when
stones are exposed to strong beam of electrons) are different
than colors in natural (mostly blue) and synthetic HPHT (mostly
green).
Should first two indicators be present,
the gem in question should be sent to a professional lab for further
study, according to Deljanin. "Our findings are based on very limited
research samples, but we are optimistic that we will solve the detection
challenges," said Deljanin, who will be studying more Apollo diamonds
over the next few months. "We are working with Apollo on both detection
and disclosure issues and plan to release a more comprehensive,
definitive report that will provide assurances to the trade about
these lab-grown gems."
Other characteristics of the limited sample studied by EGL USA researchers
were:
- Clarity of polished CVD diamonds
studied were slightly included to very slightly included
- All stones were fancy shapes or
irregular (not round)
- Weights were up to 0.45ct, depth
up to 2.50mm
- Almost all samples are type IIa
(one was a combination IIa /Ib)
- Colors are fancy light brown to
near colorless, and, according to Deljanin, might be improved
with HPHT
- No characteristic absorption peaks
in VIS-NIR spectra
- Photoluminescence could detect very
low level impurity states within the crystal structure.
For more information, contact Branko
Deljanin, at EGL USA's Vancouver lab, at 604-630-0464.
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