These 2.5 ounce gold coins were produced in commemoration of the S.S. Central America's voyage and unfortunate end in 1857. The California Historical Society went through great lengths to closely replicate the original Kellogg $50 proofs by creating dies transferred from the originals, using gold from Kellogg and Co. ingots found in the shipwreck, and striking them with a press from the San Francisco mint. An original Kellogg $50 proof would cost you the better part of $1 million. These replicas present a reasonable alternative. Struck on the dates that the ship was actually sailing in the Atlantic, this one is numbered 4,6666 out of 5,000. These are quite a bit rarer than the proof issues as several thousand went missing (likely melted) when the man that headed the recovery of the ship went missing.