Iran
Islamic Republic gold 2-1/2 Azadi SH 1358 (1979) MS66 NGC, KM1241. Absolutely striking one-year type struck by the National Bank of Iran in the first year after Pahlavi reign with radiant, virtually pristine surfaces. Reported with a mintage of only 6 pieces, however Krause lists that more are known to exist. Regardless, this is an incredibly elusive issue, currently tied for the finest-known certified example.
Estimate: 1200-1400 USD