By Mike Dougherty

PHILADELPHIA (CBS) — What is a ten-cent coin worth?  Well, when it’s the centerpiece of a one-of-a-kind coin collection, minted in 1873, the answer is millions.

This is the difference between rare and unique.  The “No Arrows” dime was minted for just one day in 1873 in Carson City, Nev.   Last night, an anonymous buyer snatched up the only one still existing, at an auction at the Pennsylvania Convention Center, for $1.84 million.

Auction president Chris Napolitano says it’s the most valuable dime ever sold.

“Rated by a professional coin grading service MS-65, it was in what we call ‘gem’ condition.”

The “No Arrows” dime was part of the Battle Born Collection at the World’s Fair of Money (see previous story) which included one of every coin minted in Carson City until the facility shut down in 1893.

A total of 111 coins from that collection sold for a total of almost $10 million.