The 1 oz American Gold Eagle Coin weighs slightly more than a troy ounce because it is struck from a 22-karat gold alloy—91.67% pure gold blended with 8.33% silver and copper for added strength and durability. This alloy increases the coin’s total weight to about 1.0909 troy ounces (roughly 33.9 grams), while still guaranteeing exactly 1 troy ounce (31.1 grams) of pure gold content.