Black gold (Jewelery)
From Wikipedia, the free encyclopedia
- Note that "black gold" is also a slang term for crude oil.
Black gold or 'grey gold' as it is sometimes referred to is a type of gold used in jewelry [1]. Though gold is known for its warm yellow color it can be produced by various methods in differing colors ranging from white to black [2]. Black colored gold can be produced by various methods.
- Electrodeposition or Electroplating using black rhodium or ruthenium. Solutions that contain ruthenium give a slightly harder black coating than those that contain rhodium [3].
- Patination by applying sulfur and oxygen containing compounds.
- Plasma assisted chemical vapour deposition process involving amorphous carbon, and controlled oxidation of carat gold containing chromium or cobalt.
More recently a laser technique has been developed that renders the surface of metals deep black. A so called femtosecond laser pulse deformes the surface of the metal forming nanostructures. The immensely increased surface area can absorb virtually all the light that falls on it and thus rendering it deep black [4][5].
[edit] References
- ^ Jewelery Technology. Retrieved on 2007-11-21.
- ^ W.S. Rapson, Gold Usage, Academic Press, 1978.
- ^ Gold In Purple Color, Blue Color And Even Black Gold. Retrieved on 2007-11-21.
- ^ Ultra-intense laser blast creates true 'black metal'. Retrieved on 2007-11-21.
- ^ Ultra-Intense Laser Blast Creates True 'Black Metal'. Retrieved on 2007-11-21.
