Colors of Gold – Purple , Blue And Black !!

This is possible by using one of two methods, the first is by formation of special gold metal compounds also referred to as Intermetallic Compounds. The second process is by forming a surface coating on gold, also referred to as Patination Of Gold. Both processes create attractive colors but they do exhibit some disadvantages over normal carat gold alloys.

Purple Gold is also referred to as amethyst or violet gold. The process to make purple gold is to alloy gold and aluminium in a certain fixed ratio. Gold content is around 79% and is therefore qualified to be referred to as 18K gold. Cast pieces of purple gold are sometimes machined and faceted to be used as ‘pseudo gems’ in conventional jewellery.

Blue Gold is also made as an intermetallic compound between gold and indium. The gold derives a bluish hue color. Manufacturing techniques are similar to those for purple gold.

Black Gold is today possible using quite a few techniques. Electrodeposition using black rhodium or ruthenium is one method. Amorphouse carbon is also used at times, with the Plasma Assisted Chemical Vapour Deposition process. Controlled oxidation of carat gold containing chromium or cobalt can also be made to yield black gold. Ruthenium containing, electroplating solutions give a slightly harder black coating as compared to electroplating solutions that contain rhodium.

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