Authentication of small diamonds

Since 2004, the Swiss Gemmological Institute – SSEF checks the authentication and the quality of colourless small diamonds (melee) batches for many luxury watchmaking and jewellery manufacturers in Switzerland abroad.

ASDI – Automated Spectral Diamond Inspection is a highly specialised instrument developed by SSEF that enables the screening of melees at a high speed and reasonable price.

Contact us

Toolbox

Pricing calculator (Excel) for ASDI authentication testing in English and French

Order Form (PDF) for small diamond testing in English and French (needs to be submitted with stones upon shipment)

Pricing and principles for authentication of melees and baguettes can be downloaded in English and French

A sample ASDI testing report for melee diamonds may be found here in English and French

Sample ASDI measurements report for melee diamonds are here in English and French

Quality control of small diamonds

The Swiss Gemmological Institute SSEF has set up a strict protocol for the quality control of colourless small diamonds (melees and baguettes), fitting with specific requirements of the watch- and jewellery industry. The detailed information available on SSEF reports help our clients to evaluate the quality of their lots of small diamonds and maintain their quality management. Our routine ensures the best reproducibility of results and provides our clients results they can trust.

We routinely control colour, clarity and cut quality of small diamonds. Each diamond that is subject to quality control is also authenticated using the ASDI instrument, with the aim of sorting out any and every synthetic diamond or diamond imitation.

Colour

  • Each small diamond is placed table down in a white folded paper under a normalised light.
  • Each small  diamond is compared to our CIBJO diamond Masterstones.
  • When checking the colour of a small diamond it is important to compare it to a large diamond masterstone. This reduces colour grading margin errors, as opposed to the comparison with a small diamond masterstone.

Clarity

  • A sortoscope microscope is used for the clarity control of small diamonds and enables the visual control of a large quantity of small diamonds.
  • The size of an inclusion may be measured with a special eyepiece.
  • Stones may be compared with SSEF clarity master stones.
  • The final purity grade is defined by means of the 10x loupe.

Cut (symmetry, polish, proportions)

  • SSEF has created a Symmetry Masterset for small diamonds. This Symmetry Masterset groups more than 30 selected diamonds from an ‘Excellent’ to a ‘Poor’ symmetry grade.
  • For evaluating the symmetry grade of a diamond we check : roundness ; eccentric or tilted or wavy tables, truncated or short facets, facets of unequal size, edge displacement ; girdle with unequal thicknesses, etc.
  • SSEF has created a Polish Masterset for small diamonds. It groups more than 8 selected diamonds from «Excellent» to «Poor» polish grade.

Toolbox

Order Form (PDF) for small diamond testing in English and French* (needs to be submitted with stones upon shipment)

Pricing for quality control of melees: sampling basis (English and French) or 100% quality control (English and French)

Pricing for quality control of baguettes: 100% quality control (English and French)

Sample reports for a batch of small diamonds may be found here in French: full lot tested (PDF) or random sampling (PDF)

*Please also note the terms & conditions for submission for quality control of small diamonds in French (PDF)

Explore our research library

2022

As in the past, the SSEF is regularly asked by the Swiss police authorities to act as a gemmological adviser in criminal cases. Usually, these are fraud cases, involving undeclared or mislabeled gemstones or their imitations. In a recent case with about 20 stones submitted by the police, we not only

2022

In 2020, a novel light source for the colour grading of diamonds was developed in a collaboration between SSEF and the Department of Physics, University of Basel (see Figure 1). In contrast to many of the models on the market, the new light source uses state-of-the-art LED (Light Emitting Diode) lig

2022

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

2021

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

2020

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

2020

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