No! A proof coin, whether it has the "S" mintmark or not, should look like these images. https://www.bing.com/images/search?...s+proof+dime&qpvt=1968-s+proof+dime&FORM=IGRE Chris
Even heavily worn a proof will still have square rims. Believe it or not the incidence of dimes without mint marks in circulation is down to less than 5%. Questions about no-mm dimes may well increase going forward as fewer and fewer are seen.
Not at all It's either Environmental damage or very bad lighting. The OP never mentioned that it looks like the clad layer seems like it's missing, so I say bad lighting.
No thats its color. Blackish in the front and a dull color in the back.where can i go to have it looked at
Defender, You probably won't like the answer, however it's a 1989 penny that has had part of the zinc core dissolved by an acid. It would be classified as 'damaged' and unfortunately has no numismatic value. All US cents minted in 1983 or later (and some from 1982) are struck on planchets (blanks) made from a copper shell over a zinc core. They are 5% copper & 95 zinc, by weight.
You are already at a place to have it looked at. Your dime was minted in Philadelphia. It is not a proof coin. It is also not marketable due to the big bad coin rolling machine putting a gash through Roosevelt's head. Your dime is worth $0.10. There is nothing more about your dime unless you want mintages, weight, diameter and that kind of technical stuff. That info is readily available in your Red Book.