France
Louis XVI Ecu 1791-M MS63 NGC, Toulouse mint, KM564.10, Dav-1333, Gad-356. A very rare better date, minted near the end of the type and exceptionally struck for an ecu of the period, with a gorgeous blend of green and blue tone on the obverse and gold and mauve on the reverse. George Sobin, researcher and collector of Ecus, only reported a single known example of the date, while a search of archived auctions yields only a single VF example. As such, this coin, likely the finest extant by a large margin, is absolutely deserving of a premium price.
Estimate: 2500-3500 USD