WIREDGOV

Diamonds come in all colours with price tags to match - ice-white, blue and pink attract high prices and stones with brown hues the least. But now that brown diamonds can be heat-treated to remove the darker colour to produce near-perfect colourless gemstones, can consumers tell the difference?

Researchers, supported by De Beers UK, have used the powerful SuperSTEM electron microscope based at the Science and Technology Facilities Council’s (STFC) Daresbury Laboratory in Cheshire to study why brown colour occurs in diamonds and what happens to heat-treated stones.

Dr Iain Godfrey carried out the research as part of his PhD at the University of Manchester. He examined the atomic structure of brown diamonds before and after heat treatment to analyse defects inside the diamonds in the form of clusters of missing atoms.

For the first time structural changes or ‘voids’ within the diamonds were seen, proving existing theories that these ‘voids’ were linked to the colour of diamonds.

Dr Godfrey says: “This research has been made possible through SuperSTEM, an extremely sensitive scanning transmission electron microscope" (STEM) which uses an electron beam to probe and image the atomic image structure of the diamond. We’ve discovered that the brown coloured stones possess many minor imperfections which are absent from the colourless stones.”

He continues: “These imperfections all add up to alter the way in which the diamond absorbs certain wavelengths of light and this is the fundamental difference between the two stones.”

David Fisher, Principal Scientist from De Beers said: “Understanding the processes taking place within diamonds will help us to develop techniques to detect whether diamonds have been heat-treated. Fundamental research at an atomic level is becoming part of work that helps ensure that when someone buys a diamond they can be confident in their purchase and reassured that treatments are fully disclosed.”

SuperSTEM is funded by the Engineering and Physical Sciences Research Council (EPSRC) and sits within the Sci-Tech Daresbury national science and innovation campus near Warrington, Cheshire.

Notes to editors

Images are available.

Interviews are available with David Fisher, De Beers UK please contact 01628 771234.

De Beers Technologies have supported research in collaboration with SuperSTEM for more than ten years.

EPSRC’s SuperSTEM facility is based at STFC’s Daresbury Laboratory near Warrington. It comprises a suite of three advanced Scanning Transmission Electron Microscopes (STEM) supported by a consortium of universities. It is at the forefront of advanced imaging and analysis for a wide range of applications.

The Engineering and Physical Sciences Research Council (EPSRC) is the UK’s main agency for funding research in engineering and the physical sciences. EPSRC invests around £800 million a year in research and postgraduate training, to help the nation handle the next generation of technological change. The areas covered range from information technology to structural engineering, and mathematics to materials science. This research forms the basis for future economic development in the UK and improvements for everyone’s health, lifestyle and culture. EPSRC works alongside other Research Councils with responsibility for other areas of research. The Research Councils work collectively on issues of common concern via Research Councils UK.