How to tokenize physical assets

There seem to be a lot of buzz words about “real world assets” on the Blockchain, and I’m trying to figure out how you can actually tokenize a real world asset like a piece of art or a bar of gold. At some point there needs to be a custodian that has possession of and can verify ownership of the asset. At the same time, that third part would have to issue a token that represents it on some Blockchain AND allow that asset to be redeemed.

Is there any project actually doing this? On paper is makes a lot of sense but in practice it’s a lot more complicated, any info would be appreciated