How to polish powder gold

Dear Sir/Madam,

I have made gold powder from amalgam. The powder is brownish yellow.
Though I went through your depletion gliding chapter, I couldn’t
understand how to brinmg shine to the gold powder properly.

Sir, when amalgam is coated on surface and fired, it seems yellow
but when amalgam alone is fired it is brown in colour. Could you
please kindly tell me why is it so?

Comercially produced bronze powder has lustre. How do they produce
lustre in bronze powder?

I will wait for your reply.
Thanking you ,
Anish