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 Silver Eagle

The American Silver Eagle is the official silver bullion coin of the United States of America. The United States Mint first released it in November 1986. It struck only in the one-troy ounce size, which has a face value of 1 dollar and guaranteed to contain one troy ounce of 99.9% pure silver. The United States Mint certifies its content, purity, and weight. Silver Eagle bullion coins, along with American Gold Eagle bullion coins are viable investment alternatives to the gold and silver bullion coins produced by other countries. To ensure wide distribution of the coins, the United States Mint awarded a contract to Grey Advertising to assist in marketing and publicizing the coins domestically and internationally. The design on the coin's obverse taken from the "Walking Liberty" design by Adolph A. Weinman, which originally had been used on the Walking Liberty Half Dollar coin of the United States from 1916 to 1947. As this iconic design had been a public favorite—and indeed one of the most beloved designs of any United States coinage of modern times, silver or otherwise—it revived for the Silver Eagle decades later. The obverse inscribed with the year of minting or issuance, the word LIBERTY, and the phrase IN GOD WE TRUST. The reverse is by John Mercanti and portrays a heraldic eagle behind a shield; the eagle grasps an olive branch in its right talon and arrows in its left talon, echoing the Great Seal of the United States; above the eagle are thirteen five-pointed stars representing the Thirteen Colonies. The reverse inscribed with the phrases UNITED STATES OF AMERICA, 1 OZ. FINE SILVER ONE DOLLAR, and E PLURIBUS UNUM as well as the applicable mintmark. Like the American Gold Eagle and American Platinum Eagle bullion coins, the United States Mint does not sell Silver Eagle bullion coins directly to the public. In order to provide "effective and efficient distribution, which maximizes the availability of the coins in retail markets as well as major investment markets" the Mint utilizes a network of authorized purchasers to distribute the coins. The coins sold in bulk at a premium over the spot price of silver. The coins sold to banks, brokerage companies, coin dealers, precious metal firms, and wholesalers that meet the following requirements. Be an experienced and established market maker in silver bullion coins. Provide a liquid two-way market for the coins. Be audited annually by an internationally accepted accounting firm. Have an established broad base of retail customers to which to distribute the coins. Have a tangible net worth of $5 million. Authorized purchasers must order a minimum of 25,000 coins, which they sell to secondary retailers that sell them, in turn, to the public.