Russia
R.S.F.S.R. silver Proof 50 Kopecks 1921 AГ PR66 NGC, Leningrad mint, KM-Y83. Obv. National arms. Rev. "50" in star with date below. Appealing reddish-blue patina over surfaces free of notable marks. The fields are nicely mirrored and the strike bold. Only one piece has been certified finer by NGC.
Estimate: 4000-5000 USD