Gold coins were used as the form of currency in the earliest days of the civilization. But the coins are considered as a form of investment in these days. Bullion gold coins are especially well recognized for the investment purpose. The price for gold coins has a tendency to fluctuate a lot from a day to day depending upon the gold prices. Each and every country has an official bullion gold coin. 'American Eagle' gold coins are the official bullion gold coins of USA.As the official bullion gold coins of USA, the 'American Eagle' gold coins are certified under the 'Gold Bullion Coin Act' of 1985. The US Mint released it for the first time in market during 1986. The 'United States Congress' authorized these gold coins too.The 'American Eagle' gold coins are available in different weights of four kinds. These gold coins are available in 0.1, 0.25, 1/2, and 1 oz. The unit of 'Troy Ounce' measures the weights. These gold coins are made of 22-karat gold. So, 91.67% of purity in gold is assured in these gold coins.