Probably Balkan, made to go in a Vasilopita or Basil cake. Only one per cake, and the recipient gets good luck for the year to come. A bit like silver 3d in a Christmas pud, it's an Orthodox tradition for, I think, New Year. You see plenty of these in brass or gilt, some of which have Greek lettering but nearly always with an impossible date. A bit like brass Spade Guineas. Gold coins are rare, but not unknown.