I'd be careful. There's really nothing special that blockchain adds to gold. The vault can already give you an account and a balance and let you buy tiny shares of gold. Putting it on a blockchain seems kind of pointless to me. Maybe it avoids KYC regulations, but then I bet it's way more likely they'll eventually be dishonest and not pay out the gold they owe people.

Nothing against gold, but I'd stick with reputable and regulated vaults if you want digital shares.