Facts about Gold

Since ancient times, gold has been used to create the finest objects of art, religious articles and fine jewelry. Because gold can be mixed with other metals to create different colors and karats, it is one of the most popular metals for jewelry today in the United States and Europe. 

The most common marks for gold jewelry are 18K or 750 (signifying 75% gold), 14K or 585 (58% gold), and 10K (42% gold). Jewelry made of higher-karat gold is more yellow in color and slightly softer than gold jewelry made of lower-karat gold, which may include copper, silver, zinc, or other metals.

Pure gold (which is always yellow) is too soft for jewelry use. The metals that are mixed with pure gold for strength can also modify the color of gold resulting in different shades of yellow, white, and pink gold. White gold was originally developed to imitate platinum, and is usually an alloy containing 25% nickel and zinc. If stamped 18 karat, it would be 75% pure gold.

See here a demonstration of gold craftmanship designing a gold ring from raw gold. 

White gold which is most often rhodium plated is something of a misnomer. Gold is actually yellow, and what jewelers call white gold today is an alloy (mixture) of gold and a white metal – usually nickel, silver, or palladium (another member of the platinum family). Metals known as white are actually more of a gray color, so white gold has a yellowish cast. The higher the karat weight, the more gold there is in the alloy, the more yellow the cast appears. Since the wearer of white gold is looking for a bright white look, a very thin layer of rhodium electroplating is used to make that jewelry shine. White gold plated with rhodium will also keep its good looks longer - rhodium will not tarnish or discolor, and since it is a harder substance, it is much less likely to get scratched. 

Care of Gold 

To keep gold gleaming, rub it with a soft chamois or clean it with a few drops of dishwashing detergent and gently brush away dirt with a soft toothbrush.