Identification of Diamond by UV - Hands on Demonstration

Speaker's profile:

John Chapman

BSc (Physics) MAIP

With over thirty years of experience working in the diamond industry, John Chapman has gained expertise in multiple areas. These range from technical design of equipment, analysis of microdiamonds at the exploration stage, to gem-setting in jewellery.

Prior to his work in the diamond industry John trained at an intellectual property firm in Adelaide and also worked in equipment design (laser and imaging) for optics companies.

From 2003-2005 he was the principal editor for the periodical Rough Diamond Review and currently, he is on the editorial board of The Australian Gemmologist and is Chief Editor of the Mediterranean Gemmological and Jewellery Conferences. From 2015-2017 John was the Chairman of the Western Australian state branch of the Australian Institute of Physics.

Instrument information - The DOVE

The Dove is tailored for use with diamond, specifically for colourless D - J colours, though it may have use for coloured diamonds and other gems. It is characterised by using 220 nm Deep UV (DUV) that produces different luminescent reactions in diamond depending on their origin. Natural diamonds will fluoresce blue and not phosphoresce, while synthetic diamonds will either fluoresce a non-blue colour (purple, orange, yellow, green) or phosphoresce. Imitations such as CZ and moissanite are generally inert. Unlike the Jewellery / PL Inspectors, no comparisons have to be made between reactions from two different UV wavelengths.

In 99% of instances the reaction colour and phosphorescence from DUV are enough to identify if a diamond is natural or synthetic. This 'single view' ability enables inspection of jewellery that is larger than the viewing area, such as tennis bracelets or necklaces, by scanning over the piece and observing the reaction colour. LW is provided for instances where there is an anomalous reaction - yellow or phosphorescence among a collection of naturals, as these anomalous diamonds will exhibit bright fluorescence under LW, unlike with synthetics which are not very reactive to LW.

No apps are needed to use a Dove, though one is provided on the Gemetrix app in case a photo record or DUV / LW comparison is needed.

The components for a Dove are significantly more expensive than a Jewellery Inspector and hence a Dove is more expensive, but much less than comparative models which use the same deep UV wavelength.