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1. (WO1998052773) MARKING DIAMOND

Pub. No.:    WO/1998/052773    International Application No.:    PCT/GB1998/001493
Publication Date: Fri Nov 27 00:59:59 CET 1998 International Filing Date: Sat May 23 01:59:59 CEST 1998
IPC: B28D 5/00
B44B 7/00
Applicants: GERSAN ESTABLISHMENT
SMITH, James, Gordon, Charters
GUY, Keith, Barry
POWELL, Graham, Ralph
GAUKROGER, Michael, Peter
Inventors: SMITH, James, Gordon, Charters
GUY, Keith, Barry
POWELL, Graham, Ralph
GAUKROGER, Michael, Peter
Title: MARKING DIAMOND
Abstract:
In order to provide an invisible information mark on a facet of a diamond gemstone, a plasma resist is applied to the whole of the exposed surface of the gemstone, a layer of gold is applied to the facet in the region where the mark is to be formed, a selected zone of the metal and resist layers is ablated by ultraviolet laser ablation to form a mask on the facet, an electrical connection is provided to the metal layer, and the facet is plasma etched through the mask in order to apply a mark of appropriate depth, the resist and metal layers subsequently being removed.