-snip-

Also, it may behoove you to rephrase your offer to accept lenders from around the world, but you will need to find a trusted escrow agent in Germany.  I don't know if it'll make much difference, but it might.  I wish you luck with the help you need, but I doubt your offer is going to get much traction.

Maybe your brother can help you with the loan, since he's already in possession of the jewelry and aware of it's authenticity (not that he would need collateral since he's your brother.)  Have you asked him?