In reply to mypyrex:
I caught a bit of a consumer programme where they tried a few places and the postal ones were the worst.
It's a simple matter of weight if they have no value in the design. An honest jeweller will give you the weight. Then you only have to phone around for the best price per kg. Then take it in yourself.
As you're selling to someone who sells to someone, etc, etc until it gets to someone buying enough to actually melt it down you won't get the metal market price.
Do Johnson Matthey precious metals buy direct? We got a surprising payment when a member of staff retired and the Pt and Pd chemicals from an old project were cleared out and sent back to them.