Expert: PAPAJACK - 7/17/2007

Question
The reverse is upside down.  I have checked a bunch of 1990 d quarters and this is the only one with the reverse upside down.

Is it worth anything besides 25 cents?  In average condition.

Answer
Hello Bill,                       

An error like a rotated die, of more than 45 degrees, on a coin is a good find and would be desirable to error collectors. It would start at a price above $5.00 if authentic.
That it is exactly 180 degrees off and I have not heard of any others is odd. You may have an altered coin. I am not very involved with Error-Coin-Collecting; you should take the coin to a dealer for advice.  
If you write back with the general location (nearest large cities) and telephone area code or codes and some zip codes in your area, I can direct you to an AMERICAN NUMISMATIC ASSOCIATION MEMBER/DEALER near there. They are ethical and trustworthy.

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Thank You and Good Luck

PapaJack