If you bought it there, no matter what stones are in the piece, they will buy it. If you did not buy the piece there, and it is all diamonds, they will buy it. If it has sapphires or rubies in it, they won't do it, but they will refer you to someone.
You can, their warranty would cover both from my understanding.
Yep i buy diamond and gold from there. But not as a complete set
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