Colored gold

Colored Gold is the name given to any gold that has been treated using techniques to change its natural color. Pure <a href="/facts/Gold/1znknojp">gold</a> is slightly reddish yellow in color, but colored gold can come in a variety of different colors by alloying it with different elements.
Colored golds can be classified in three groups:: 118 

<ul><li><a href="/facts/Alloy/I7w7WQWR">Alloys</a> with <a href="/facts/Silver/xXe41BGg">silver</a> and <a href="/facts/Copper/I8PEE8oX">copper</a> in various proportions, producing white, yellow, green and red golds. These are typically <a href="/facts/Ductility/SBJsahEk">malleable</a> alloys.</li>
<li><a href="/facts/Intermetallic/nnzksayl">Intermetallic</a> compounds, producing blue and purple golds, as well as other colors. These are typically brittle, but can be used as gems and inlays.</li>
<li><a href="/facts/Surface_finishing/Udeh3cxF">Surface treatments</a>, such as oxide layers.</li></ul>
Pure 100% (in practice, 99.9% or better) gold is 24 <a href="/facts/Fineness/Wc5HBM0I">karat</a> by definition, so all colored golds are less pure than this, commonly 18K (75%), 14K (58.5%), 10K (41.6%), or 9K (37.5%).

Colored gold open-in-new

Colored gold