Could This Really Be An 1883 $20 Proof Coin?

The 20 bucks to send it to ANACS is worth it beyond a doubt. Send it in.

Yes, possibly. PCGS' Details code "90" covers both counterfeits and altered date/mint mark, so that numeric designation may be the only thing the submitter gets. In this case, that could be a $1600 swing in value, as an altered mint mark would still retain the gold bullion value while an off-metal fake would retain nothing.

NGC's description of the same makes me think they will inform the submitter of the exact reason (.pdf link):

http://www.google.com/url?sa=t&rct=...C4QFjAA&url=http://www.ngccoin.com/pdf/details_grading_brochure.pdf&ei=LTmpUIjBLJGF0QHB9YHoCQ&usg=AFQjCNEL8gdKDNp3-fkd-4vCkToBGI2JTw&cad=rja

ANACS I'm unsure of; their website is insufficiently clear on the subject. They are, however, the most approachable of the three major TPG's, and most likely to be willing to talk on the phone about the coin.

Judging from ray123's pics and measurements, I'm guessing this is an actual Double Eagle, whether the mint mark has been altered or not. The detail is just_too_nice and the dimensions are spot-on. Yes, I understand that this could be achieved with an off-metal counterfeit, but if so, it's of such quality that it would have value to the world of numismatics just to be known.

If it's an altered mint mark, it still has the intrinsic value of its' gold, which is over $1600 and the OP can recover most of the investment.

My working theory remains that it's a genuine coin with an altered mint mark. An 1883-S needs to be better than MS61 to have any added value to speak of, so a slightly-circulated coin would be a very tempting piece for the morally-challenged to try to alter.

The coin has definitely been cleaned even if it is a cleaned proof, it would still be of significant value. One thing I notice in the halos around the stars, design, hair, and date is the luster resembles a business strike much more than a proof. Another thing I notice is the rounded rims which is more characteristic of a business strike than the sharp rims that you usually see on a proof. In all, I am doubtful it is a genuine 1883 proof $20 though it still could be genuine coin made at a mint other than Philly.

Ray123, please be sure to keep us updated on this coin. Also, if you are sending it to ANACS, don't be shy. They are willing to talk on the phone. I disagreed with a grade on a coin, called and spoke directly to James Taylor, who was the CEO at the time, and got it regraded. He then explained to me why they reached the grade they did and, after that, I agreed with him. You may not be able to speak to the CEO, but they are very approachable, or at least they were a few years ago. I send almost all of my coins to PCGS these days.

I got the coin back. It was rated "N9, mint mark removed."

Once again, CCF provides excellent advice and support to a collector on a potential high-value piece. Kudos to everyone for their professionalism!