To say the 1849 Coronet Head gold $20 double eagle is rare would be an understatement. According to Las Vegas Jewelry and Coin Exchange, there might be only one left out in the world today.

Minted in 1849, this rare coin easily falls into the million-dollar club. Made from 90% gold and 10% copper, this coin weighs just over 33 grams. It’s valued at around $15 million.

The auction house did not give any information about who bought the coin. Prior to 1849, the highest denomination for a gold coin was $10, known as the eagle. The $20 double eagle was authorized ...