Gersan Establishment

Anstalt Gersan

Martin Cooper

Martin P Smith

James Gordon Smith

Christopher M Welbourn

Andrew D Stewart

Paul Martyn Spear

Philip Maurice Martineau

Robin W Smith

James Gordon Charters Smith

Daniel J Brink

Marie-Line Rooney

Ricardo Simon Sussmann

In order to produce on the table of a diamond gemstone (,), an information mark which is invisible to the naked eye using a &times;10 loupe, an ultraviolet laser (,) having a wavelength of 193 nm is used in association with a mask (,) to irradiate the surface of the stone (,) at a fluence of less than 2 J/cm,per pulse and with not fewer than 100 pulses, in the presence of air which reacts with the diamond (,) and causes the mark to be formed without any darkening which is visible when viewing using a microscope.

Marking diamond

Examining a diamond

Method and an apparatus for testing whether a diamond has a layer of

Detecting diamonds in a rock sample

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

Making an elongate cut using high energy radiation

Sensing a narrow frequency band of radiation and gemstones

Growing community of inventors

Marlow, United Kingdom

Martin Cooper