Rose gold consists of an alloy that contains gold and copper in varying percentages. The name comes from the reddish color, which is caused by the copper content. Higher copper content alloys yield red gold, while those with a higher gold content are referred to as rose or pink. Crown gold is one example that uses a very high percentage of gold and a low percentage of copper. Rose gold has also been used for a variety of other applications, such as the construction of jewelry and musical instruments.
A variety of different hues can be obtained by alloying gold with silver and copper. Adding silver tends to make the alloy whiter, and copper turns it more red. Altering the ratios between these metals can also produce greenish tints. Rose gold typically contains a high ratio of gold to copper, though some silver or zinc is sometimes used as well. In addition to altering the color for aesthetic purposes, copper is sometimes alloyed with gold to create a more durable metal than pure gold bullion alone.
One widespread use of red gold is in decorative jewelry, where a common ratio is thee parts gold to one part copper by mass. Since karats are a measure of purity, and 24 karat is considered 100% pure, this particular alloy results in 18 karat gold. The rose red color is often thought of as aesthetically pleasing, though pieces made of alloys such as this are much more resistant to wear than gold alone. Copper is a more durable element than gold, and alloys of the two tend to be somewhat more resilient.
Crown gold is another specific alloy that takes advantage of the durability of by copper. This alloy was originally used to mint gold crown coins in England during the 1500s, and is defined as being 22 karat gold. A purity of this level corresponds to over 91% gold and less than 9% copper. This ratio is the highest karat value possible for rose gold before the alloy will typically be considered yellow.
Rose gold has also been used to construct instruments, in which case it will typically be cast as a solid object rather than plated. Higher copper contents are sometimes used for applications such as this, and a 50% mixture of each metal can be used. The exact mixture can differ, and rose gold flutes can typically be found in anywhere from nine to 19 karat gold.