A process for imparting and enhancement of colours in gemstone minerals and gemstone minerals obtained thereby

摘要

A process for imparting colour to, or enhancing the colour of, gemstones such as topaz and sapphire involves the coating of the gemstone substrate with a colour-inducing or colour-enhancing material, and heating to a temperature in the range 900°C to 1,250°C for a period of 30 minutes to 10 hours. Suitable coating materials are metals, metal oxides, other metallic compounds, and alloys. By appropriate selection of coating material, for example from among cobalt, iron, chromium, and compounds and mixtures thereof, a range of colours including blues, greens, oranges and reds may be produced.