Gersan Establishment

Other

Element Six Gmbh

Paul Martyn Spear

Christopher M Welbourn

Philip Maurice Martineau

Martin P Smith

Martin Cooper

Daniel James Twitchen

Geoffrey Alan Scarsbrook

Andrew D Stewart

Robin W Smith

Ian Friel

Stephen David Williams

James Gordon Smith

Daniel J Brink

A method of producing a CVD single crystal diamond layer on a substrate includes adding into a DVD synthesis atmosphere a gaseous source comprising silicon. The method can be used to mark the diamond material, for instance to provide means by which its synthetic nature can more easily be determined. It can also be exploited to generate single crystal diamond material of high color.

Diamond

A method of incorporating a mark of origin, such as a brand mark, or fingerprint in a CVD single crystal diamond material, includes the steps of providing a diamond substrate, providing a source gas, dissociating the source gas thereby allowing homoepitaxial diamond growth, and introducing in a controlled manner a dopant into the source gas in order to produce the mark of origin or fingerprint in the synthetic diamond material. The dopant is selected such that the mark of origin or fingerprint is not readily detectable or does not affect the perceived quality of the diamond material under normal viewing conditions, but which mark of origin or fingerprint is detectable or rendered detectable under specialised conditions, such as when exposed to light or radiation of a specified wavelength, for example. Detection of the mark of origin or fingerprint may be visual detection or detection using specific optical instrumentation, for example.

Method of incorporating a mark in CVD diamond

Examining a diamond

Distinguishing natural from synthetic diamonds

Distinguishing natural from synthetic diamond

In order to sort diamond-bearing ore particles conveyed on a wide belt, exciting radiation strikes the belt along an extended line. Diamonds are detected by passing the emitted radiation through a narrow band pass filter and sensing the Raman radiation with a photo-multiplier tube. Only axial-parallel rays passing through the filter reach the photo-multiplier tube. An array of side-by-side converging lenses can be used, the lenses being of rectangular shape as seen looking along the optical axis with their long axes at right angles to the line of radiation. The ore particles are in the plane of the foci of the lenses, so that radiation emitted by each particle is passed in parallel rays through the filter. In order to stop rays having an angle of incidence greater than the maximum permitted, to avoid identifying non-diamond material as diamond, a further converging lens is used to focus the rays at the plane of a telecentric stop. The stop stops rays having too great an angle of incidence. The position of the diamond can be detected for instance by a CCD array or by a time domain technique. The apparatus can be monitored by giving a signal when the radiation from tracer stones and holes on either side of the belt, differs from predetermined values.

Sensing a narrow frequency band and gemstones

Sensing a narrow frequency band of radiation and gemstones

Growing community of inventors

Maidenhead, United Kingdom

Paul Martyn Spear