So I was recently going through some of my grandfather's old coins and found a 1975 dime with no mint mark in a hard plastic case that was made into a key chain. I know nothing about coins, and i know there is almost no chance this is THE coin, but wanted to ask some people that knew something about it. The coin seems to be in great condition in the plastic. I am posting some pictures of it. Is there any way to differentiate between a proof and a normal dime? Any help would be greatly appreciated. Thanks
A proof, especially during this date, will exhibit mirror surfaces. This example is a business strike minted in Philly = satin like surface. The Philly coins were made without a mint mark.
The one you want is the proof w/out a mintmark. These proofs normally bear an 'S' mintmark, but the mintmark was mistakenly omitted from a single die dated 1975. Coins struck from this die will not exhibit any mintmark. The 1975 business strikes do not bear mintmarks, but that is as intended.
Did something important to your grandfather happen in 1975, like a son or grandson being born? Guessing it is a sentimental piece.
I don't believe that's the valuable proof and if I saw it in hand I believe I'd be certain it is not. But I can't rule out that it is the valuable proof from the photo. It would help if you could get a picture of the rim around either side of the coin or a light reflecting from the surface.
