It uses the term "stablecoin" in the URL and the term "blockchain" on the site, so yes. It would be impossible otherwise. This in effect means that (Provided they're not outright scammers), they're using an inefficient database system to give you a capability (Precious metal custodianship) which has existed for at least thousands of years. At best, the digital online capability can be said to have existed for the last 20 years. They likely use these blockchain / stablecoin terms to skirt legal custodian laws which they are required to comply with.
'Blockchain' recording an extrinsic asset to the blockchain itself is impossible. All you've created is an extremely inefficient database for custodianship:
