Colored Gold Metal Alloys
Gold colors: green, rose and white are colored gold metal alloys. Gold colors are made by combining silver, copper, palladium & other metals to make gold metal alloys. Gold colored jewelry can also be purple, blue, black etc., being intermetallic gold colors.
Photo by hto2008Pure 24k gold is only ever one colour: yellow. Gold does not occur naturally as rose, white, or green gold. Most other pure metals are gray (grey) or silvery white: only gold (yellow), and copper (red) have color. This color is determined by the density of loosely bound electrons which fall into the visible range for gold and copper, but in the ultraviolet range for all other metals. Any carat (karat) other than 24k gold (pure gold) is called an alloy. Gold is mixed with other metals to produce alloys, simply mixtures of two or more metals.
Pure, 24k gold is soft. Alloying it with other metals alters its hardness, ductility, melting point and color (and other properties). Colored gold has various hues produced by alloying gold with other elements. Gold Alloy
In this article we are interested only in the colour variations that occur when varying weight amounts of other metals are used with gold.
White colored gold
White gold is not a special form of gold. White colored gold is a true carat gold, just like yellow or rose carat gold. It is a gold alloy that looks white rather than yellow. White gold is made from a gold-silver alloy. 18k white gold alloy consists of: 75wt% gold and 25wt% silver. White gold.
Rose colored gold
Rose gold has a less subtle reddish hue than red gold, but is darker than pink gold. Rose colored gold is made from a gold-silver-copper alloy. It has less copper in the gold alloy than red gold, but more than pink gold. Typically, 18k rose gold alloy consists of: 75wt% gold and 25wt% copper, or 75wt% gold, 21wt% copper and 4wt% silver. 9k rose gold has a darker rose-copper colour than 18k rose gold. Tumbaga is a gold and copper alloy. Red gold, Rose gold and Pink gold.
Green colored gold
Green gold is not really green. Green gold is a subtle greenish yellow. Green colored gold is made from a gold-silver-copper alloy with limited amounts of copper metal. This was known as Electrum by the Lydians almost 3,000 years ago. Green gold.
Yellow colored gold
24k gold is yellow, but it is not an alloy, as it is pure gold. Yellow colored gold alloys are created in order to add particular qualities to the gold alloy, and generally to lower the cost base and increase the profit base. The differing yellow hues of yellow colored gold are due to the differing admixtures of alloying metal. Silver, copper, zinc and other metals are alloyed together with the intention of keeping a yellow color, whilst creating an alloy with better qualities for the manufacture of jewelry.
Intermetallic colored gold metal alloys: Colors of gold jewelry
Photo by SwamibuIntermetallic gold alloys can be produced in various colors including purple, blue, black, grey. brown and apricot, with subtle differences in hues within the color bands. They are brittle and used in jewelry as gemstones would be used.
Purple colored gold
Purple colored gold, amethyst colored gold, or violet colored gold are one in the same thing. They are gold-aluminum (gold-aluminium) alloy colors. Purple colored gold alloy is created when gold and aluminum are mixed in the ratio 79:21 by weight.
The conventional jewellery application of purple colored gold is in form of cast and ground items, which are set similar to gemstones. Purple gold.
Blue colored gold
Blue golds are gold-indium, gold-gallium intermetallic alloys. Blue colored gold is produced in various hues: clear blue gold, bluish hued gold, rich sapphire blue gold, blue gold and blue-green gold. The jewelry trade does not seem to have taken up the use blue gold intermetallic compounds in any quantity, except notably by Steven Kretchmer. Blue gold.
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