| 摘要 |
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.
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