There are certainly some that were made in limited numbers and then mostly melted (ie; HK 1031, of which 6 of the "original 5 struck" survive... there may be some shenanigans going on there): https://coinweek.com/extremely-rare...to-be-offered-at-july-21-austin-auction-sale/ But, I would say that most are referring to a unique coin as in one that has only a single certified example. I have a token like that:
This might be of interest to somebody here: https://www.biddr.com/auctions/jacquier/browse?a=4892&l=5920781
This might interest somebody here: https://auctions.cngcoins.com/lots/...os-195mm-647-g-10h-reduced-standard-superb-ef
This coin is extremely rare: https://www.sarc.auction/ALMORAVID-...-AV-dinar-4-17g-Dar-a-AH542-bold-XF_i53867677
Yes, he was the last sultan of the Emirate of Granada, but I don't want his coin, I would like to acquire a Gold Dinar of either Muhammad V or Yusuf I.
This is supposedly very rare: https://auctions.thecoincabinet.com...vladimir-olgerdovich-1362-1394-silver-denaras
Those coins are awesome! Some folks say "money is not everything" I would say it sure comes in handy with nice coins like that. I could spend a Billion on sixbid in one year easy/ thats only going after high quality coins.