1975 "no S" proof dime, one of two known to exist, to be auctioned at over $500,000.

Three Ohio sisters have inherited a rare 1975 "no S" proof dime, hidden in a bank vault for over 40 years. This unique coin, one of only two known to exist without the San Francisco mint mark, is expected to sell for over $500,000 in an upcoming online auction. Their late brother and mother purchased it for $18,200 in 1978. The dime will be showcased at a Tampa, Florida coin show before the auction closes in late October.