Gold does not become real when it reaches a vault.
It already exists physically within the earth. Modern exploration, drilling, sampling, assay and geological modelling allow substantial underground gold deposits to be identified, measured and independently verified long before that gold is mined.
The central idea is not to pretend that underground gold is identical to refined bullion. It is to recognise that independently verified underground gold can represent a real and measurable economic foundation long before it reaches a vault.