Watch List notes:

Foreign Coins, Switzerland, 20 francs, 1888B, diad. head l., rev. shield of arms within wreath (KM.31.3; Fr.497), certified and graded by PCGS as Mint State 64
One of the rarest regular-issue Swiss gold coins, with a mintage of only 4,224 pieces.
Estimate: 4000-6000 GBP