Scuba,
Anything there that is flat melted out, seems to go well for me, but the moment I do the "free stone removal" and they do the chemical bath, I lose 10%, instantly. They tell me it's because it's hard to recover, but I've found that it just doesn't make sense. Gold is gold, whether it's chemically recovered or melted. It's not like it disappears. I'm only bringing this up, because I wonder if you had yours melted, or chemical bath'd. If it's the latter, it seems on par with what you've experienced.
I also don't send them diamonds any more. They used to give real bids... the last time they bid, they bid on total weight, and one of the stones was a 3/4 carat stone... they initially offered me $60 for it. I knew the wholesale (not retail) was 997. I figured I should get at least HALF that in a bid... I told them so, they came back with a $250 bid. I told them I'd accept, but I knew they were undercutting, but I'd liked working with them in the past, and that was a gimme for them. They said, "thanks!" I don't think they realized I'd never do it again.
I now rip out all my stones with pliers before sending, and I'm back to the 98% with scrap melt. It's the only way I'll do it. Too expensive to lose 10% just because there's a stone in it. Plus, I can sell diamonds at a higher rate than their bogus bids.
Cheers,
Skippy