What is the value of a 2001 platinum 20 coin in 14k gold pendent with black onyx back?

8-9-11>>> The West Point Mint only strikes $100, $50, $25, & $10 platinum coins, no $20.00 coins. A $25 coin is a quarter-ounce of platinum, so if the coin is real, it's value is about $400.00 today.