How rare are error coins in US Mint Proof sets? I received a set for Christmas and 1 coin appears flawed.?

Errors are quite rare in proof sets but having a damaged coin in one is not. Though not real common defective coins do get into the sets more times than the mint likes. The shinny spot could be from grease from the minting press or an oil. You did not list a date but if a 2008 they would take it back and send another. If older than that you are stuck with it unless the person takes it back you bought it from. That is why it is wise to check all mint and proof sets. It does not ad value to your set but takes it away.

Us Mint Proof Set

The 1992 sells for $7.ninety 5, 1998 $23.ninety 5, 1996 $17.ninety 5, 1995 $40 4.ninety 5, 1997 $37.ninety 5, 1994 $thirteen.ninety 5, and the 1999 $sixty 4.50. of direction sellers pay much less. the charges have been taken from an advert in Coin international magazine, it is the uncomplicated sell cost via particularly some sellers. you presently comprehend what the sellers are merchandising them for, so next step is as much as you. sturdy success.

First, it seems errors are quite rare in proof sets. "A few broadstrikes, off-centers, double strikes in collars and off-metals have been known to be found in sealed proof sets. Proof errors are aggressively sought after by many error collectors." (quoted from http://minterrornews.com/priceguideprooferrors.htm...

Second, you are one lucky collector! You might want to be asking a different question. "How much can I get for this coin?" Looks like two thousand to ten thousand might be the value price for your coin. Maybe a lot more if the error is of an unusual type.

that could be worth 100-1,000 dollars they are very rare