Among all the famous American signatures — including Abraham Lincoln and George Washington— why is the autograph of Georgia founding father Button Gwinnett the most valuable?

It’s because he was obscure before signing the Declaration of Independence in 1776, and he was killed 10 months later in a duel with a rival. Consequently, only 51 examples of his signature are known to exist, said Bobby Livingston, of RR Auction in Amherst, New Hampshire, who is putting a Gwinnett signature on the block this Saturday.

This particular signature is on a 1773 document relating to debts owed on Gwinnett’s Georgia businesses. It’s being sold as part of a full set of 56 signatures from the signers of the Declaration, called the Proctor-Sang-Newell collection, expected to fetch between $1.2 million and $1.5 million. The Gwinnett autograph alone would be worth more than half of that, said Livingston. A solo Gwinnett autograph sold two years ago at Sotheby’s in New York for $722,500.

Anyone assembling a full set of autographs from the signers must have Gwinnett’s hand, but he’s the hardest to get, which has also driven up his value.

“We’ve been in [the autograph] business 32 years, and I’ve never even held one in my hand,” said Livingston of the Gwinnett signature. “It’s scary, it’s rare, and it’s the ultimate prize.” Information: www.rrauction.com/