About Gold

The proportion of gold in jewelry is measured on the karat scale.  The word carat comes from the carob seed, which was originally used to balance scales in Oriental bazaars.  Pure gold is designated 24 karat and is used in those parts of the world where jewelry is purchased as much for investment as it is for adornment, but it tends to be vulnerable to scratching. Elsewhere, it is usually mixed, or alloyed, with other metals.  Not only do they harden it, but influence the color; white shades are achieved by alloying gold with silver, nickel or palladium; red alloys contain mainly copper.  A harder alloy is made by adding nickel or a tiny percentage of titanium.  Since nickel is the most popular alloy used in white gold, it is important to note that some people may be allergic to nickel.  People with this sensitivity can avoid problems by choosing 18 karat gold, instead of 14 karat (since there is more pure gold and less alloys in 18K), or by choosing platinum settings.

The most widely used alloys for jewelry are 18K, (75% pure gold), and 14K, (58.3% pure gold), although 9K is popular in Britain.  Portugal has a unique designation of 19.2K.  In the United States 14K predominates, with some 10K.  In much of the Middle East, India and South East Asia, jewelry is traditionally 22K (sometimes even 23K).  In China, Hong Kong and some other parts of Asia, "chuk kam" or gold jewellery of 990 parts per 1000 fineness (almost 24K) is popular.

Source: World Gold Council Web Site