Ron Guth:
In 1840, the Philadelphia Mint struck Proof versions of the new Seated Liberty Dollar. Very few coin collectors existed in America during the 1840s, and even fewer had access to the Mint, or even knew that it was possible to buy or trade coins there. Thus, the number of Proof coins struck was very small, especially for the silver and gold denominations, which were inherently more expensive. Conventional wisdom states that the Mint produced between 15 and 20 Proof Silver Dollars. Essentially, this is a guess based on the number of survivors, not on any hard and fast data. The PCGS Auction Prices Realized listing cited separate appearances (not counting no sales) as of October 2015. Combining duplicates brings the total down to the prevailing range of 15-20 coins. Most citations refer to PR62 to PR64 examples. Highlights include a couple of PR65's and only one Cameo (PR64). Not surprisingly, the sole Cameo example set the price record of $85,188 when it sold in 2013 -- even though it is not the highest-graded Proof 1840 Dollar (from a technical standpoint). The only known PCGS PR65 example shows clear evidence of at least three different strikes; multiple strikes are the reason Proof coins from the 1800s look so different than those struck for circulation.