According to Jeff Garrett and Ron Guth in their Encyclopedia of U.S. Gold Coins, 1795-1933, 'The 1858-S is a low-mintage, low-population coin that has proven to be a resilient rarity over the past two decades. While the populations of other dates have swelled, that of the 1858-S issue has remained small, creating a new appreciation for this date. It is nearly as rare as the much more highly regarded 1858 eagle, but unlike the 1858, no Mint State examples of the 1858-S are known.'