Element Six Technologies Limited

De Beers UK Ltd

Gersan Establishment

Anstalt Gersan

Michael Peter Gaukroger

James Gordon Charters Smith

Keith Barry Guy

Peter Stanley Rose

Robert Charles Burns

Grant Charles Summerton

John Olaf Hansen

Simon Craig Lawson

Timothy Patrick Gerard Addison

Daniel James Twitchen

Philip Maurice Martineau

Ian Friel

James Gordon Smith

Graham Ralph Powell

An apparatus for viewing images of a gemstone is described. The apparatus comprises a support structure for supporting the gemstone at an observation position. An illumination structure comprises a plurality of directional light sources directed towards the observation position so as to illuminate the gemstone. The support structure and illumination structure are relatively rotatable relative to one another about a rotation axis. An imaging device is arranged to obtain images of the gemstone at the observation position at a variety of relative rotational positions between the illumination structure and support structure: the imaging device has an imaging axis passing through the observation position. The support structure is arranged so that the gemstone can be placed at the observation position in such a way that the normal to a selected facet of the gemstone is within a range of tilt angles from the rotation axis. The arrangement of directional light sources is such that, for any tilt angle within the range, at least one of the directional light sources will be specularly reflected from the selected facet into the imaging device for at least one rotational position of the support structure.

Gemstone viewer

The invention relates to a single crystal CVD diamond material, wherein the extended defect density as characterized by X-ray topography is less than 400/cm2 over an area of greater than 0.014 cm2. The invention further relates to a method for producing a CVD single crystal diamond material according to any preceding claim comprising the step of selecting a substrate on which to grow the CVD single crystal diamond, wherein the substrate has at least one of a density of extended defects as characterized by X-ray topography of less than 400/cm2 over an area greater than 0.014 cm2; an optical isotropy of less than 1&#xd7;10-5 over a volume greater than 0.1 mm3; and a FWHM X-ray rocking curve width for the (004) reflection of less than 20 arc seconds.

High crystalline quality synthetic diamond

This invention relates to a method of improving the crystalline perfection of IIa diamond crystals by heating the grown diamond crystals at an elevated temperature and an elevated pressure. The invention extends to grown diamond material having a low extended defect density with low nitrogen concentration.

Method of improving the crystalline perfection of diamond crystals

An invisible information mark is provided on a facet of a diamond gemstone by applying a plasma resist to the exposed surface of the gemstone, applying an electrically conducting layer of metal to the region where the information mark is to be formed, ablating a selected zone of the metal and resist layers by ultraviolet laser thus forming a mask on the surface of the facet, electrically connecting the metal layer and plasma etching the facet through the mask, thus forming a mark of appropriate depth on the surface of the gemstone.

Marking diamond

Cutting using high energy radiation

Determining the existence of misorientation in a crystal

Growing community of inventors

Hampshire, United Kingdom

Michael Peter Gaukroger