Great Britain
George IV Proof 1/2 Crown 1820 PR62 NGC, Royal mint, KM676. It appears this coin was penalized for a past light wiping of the neck and part of the face and a spot on the neck. What gets discounted is the brilliant eye-appeal, lightly amber toned watery fields, pinpoint detail, and cameo-like contrast from the fields. This is very elegant to view in hand to say the least.
Estimate: 1200-1500 USD