You remember the gold-standard and silver-standard, where currency was just a receipt for amount of precious metal in bank vault and you could at any time return the “silver certificate” and get the metal back.
This is the first NFT collection tied to real gemstones. Each token is linked to a real gemstone, and the owner of the token can agree to transfer it back to APN201 to get the actual gem in exchange.

Check out the collection at OpenSeas.