Because of the softness of pure (24k) gold, usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. Alloys with lower caratage, typically 22k, 18k, 14k or 10k, contain higher percentages of copper, or other base metals or silver or palladium in the alloy. Copper is the most commonly used base metal, yielding a redder color. Eighteen-carat gold containing 25% copper is in antique and Russian jeweler. It has a distinct, though not dominant, copper cast, creating rose gold. Fourteen-carat gold-copper alloy is nearly identical in color to certain bronze alloys, and both used to produce police and other badges. Blue gold can be made by alloying with iron and purple gold can be made by alloying with aluminum, although rarely done except in specialize jewelry. Blue gold is more brittle and therefore more difficult to work with when making jewelry. Fourteen and eighteen carat gold alloys with silver alone appear greenish-yellow and referred to as green gold. White gold alloys made with palladium or nickel. White 18 carat gold containing 17.3% nickel, 5.5% zinc and 2.2% copper is silver in appearance. Nickel is toxic, however, and its release from nickel white gold controlled by legislation in Europe. Alternative white gold alloys are available based on palladium, silver and other white metals (World Gold Council), but the palladium alloys are more expensive than those using nickel. High-carat white gold alloys are far more resistant to corrosion than are either pure silver or sterling silver. The Japanese craft of Mokume-gane exploits the color contrasts between laminated colored gold alloys to produce decorative wood-grain effects.

American Gold Eagle

The American Gold Eagle is an official gold bullion coin of the United States. Over the years, the gold Eagle from the US mint have become the USA’s most popular bullion coin, and our biggest gold coin seller by far. Each 1-ounce gold Eagle contains a full 31.1 grams of pure gold, with an additional alloy of silver and copper, bringing the total weight up to about 33.9 grams. Coins Offered in 1/10 oz, 1/4 oz, 1/2 oz, and 1 oz denominations. U.S. government guarantees them to contain the stated amount of actual gold weight in troy ounces. By law, the gold must come from sources in America, with an additional alloy of silver and copper to produce a more wear-resistant coin of .9167. It authorized by the United States Congress and backed by the United States Mint for weight and content. The market value of the coins is generally about equal to the market value of their gold content, not their face value. Gold Eagles from the U.S. Mint are the most popular gold bullion coin in this country, and now make up over 80% of the U.S. physical gold bullion market. This bullion product has been a tremendous success for the U.S. Mint.; their actual selling prices vary daily based on the current spot price of gold. The face values are proportional to the weights. The one-ounce gold Eagle has a $50 nominal face value, is 91.67% fine gold, and weighs 1.0909 troy ounces. The most popular size bullion coin issued 20 coins per Treasury tube. The half-ounce gold Eagle has a $25 nominal face value, is 91.67% fine gold, and weighs .5455 troy ounce. The least popular size bullion coin, and often the lowest mintage, it is issued 40 coins per Treasury tube. The quarter-ounce gold Eagle has a $10 nominal face value, is 91.67% fine gold, and weighs .2727 troy ounce. About the size of a nickel, it is popular in jewelry. It issued 40 coins per Treasury tube. The tenth-ounce gold Eagle is a $5 face value coin, 91.67% fine gold (22 karat), and weighs .1091 troy ounce. Smaller than a dime, it is a popular small gift item. It issued 50 coins to a Treasury tube. The obverse design features a rendition of Augustus Saint-Gaudens' full-length figure of Lady Liberty with flowing hair, holding a torch in her right hand and an olive branch in her left, with the Capitol building in the left background. The reverse design, by sculptor Miley Busiek, features a male eagle carrying an olive branch flying above a nest containing a female eagle and her hatchlings.