If it is for Proof of Funds, then my understanding is that assetts such as jewellery cannot be used.
The only asset (as opposed to fixed deposits or cash) which can be used is property - which you can prove by getting house valuations + mortgage letter/statement.
The correct procedure is to have it valued by a jeweler. But, practically it's not needed. Your own "generic" valuation (based on the market rates) or if u have their purchase invoices, r perfectly alright. I did it that way & succeeded. So did many.
Qorax
Ps.: Do not forget their Pictures, else they'd not be accepted - DANGER.