Two exceptional asteriated diamonds
by Dr. L. Speich & J.-P. Chalain, first published in Facette 27 (June 2021) Recently, SSEF received two so-called asteriated diamonds for authentication. Asteriated diamonds are rare and highly prized amongst collectors for their beautiful and unique appearance. The two stones received in our lab
Preliminary study of defocused PL measurements of diamonds
A study of nickel-bearing type Ia diamonds. IGC 2023 Proceedings, 37-39.
Treated greenish yellow diamond with brown radiation stains
Treated greenish yellow diamond with brown radiation stains. The Journal of Gemmology, 680-683.
Diamonds as a window into the earth
by Dr. L. Speich, first published in Facette 26 (May 2020) Diamond is valuable as a gemstone but it is also a mantle geologist’s best friend because it provides a rare opportunity to study processes that occur deep in the Earth. Most diamonds form in the so-called lithospheric mantle within a fairly narr
Why is a Diamond of Type IIb blue to greyish blue?
Comparing the absorption spectra of type IIa and type IIb diamonds greatly helps to better understand why a diamond of type IIb is blue to greyish blue.
ASDI (Automated Spectral Diamond Inspection)
by J.-P. Chalain, first published in Facette 21 (February 2014) In 2013, numerous trade-press articles and gemmological laboratory alerts warned the diamond industry about the presence of synthetic diamonds mixed together with, or presented as, natural diamonds. These announcements pointed out that not onl
Undisclosed natural diamonds mixed in a parcel of synthetic diamond
by J.-P. Chalain, first published in Facette 22 (February 2016) In 2016, our Diamond Department acquired a parcel of small colourless synthetic diamonds produced in Europe by the HPHT method. The complete study of these series of melee size synthetic diamonds (SSEF Research project 80602) is part of our co
CVD Synthetic Diamonds and Testing at SSEF
by J.-P. Chalain, first published in Facette 20 (January 2013) Synthetic diamonds have been present in the gem trade for over two decades. Recent financial investments and advances in technology have now made them more affordable both in terms of price and availability. The SSEF has been following synthetic di
The Detection of HPHT-treatment of Diamonds at SSEF: 20 Years later
In 2000, SSEF announced that it was able to identify the HPHT treatment of type II diamonds. About 20 years later, this article summarizes how we were able to achieve this breakthrough and which people from the trade and other research institutions were involved in this important step.
How Diamonds Salted Inside Batches of Synthetic Diamonds Creates Confusion
The diamond trade today is seriously concerned about synthetic diamonds mixed in with parcels of natural diamonds; however, we also propose here that the opposite situation of natural diamonds mixed in with batches of synthetic diamonds is also something to be concerned about and will in the near future be a (