You can already trade fusion powder, by having a player give you all the gems + shards, then use your powder to fuse the gems for them, charging a fee or not.
With friends this works fine, but it is open to people scamming others I guess, if someone is foolish enough to trust a complete stranger with all their gems.
Would it be better to unbind them? and make them a new trading commodity?
I'm not sure, but it is worth discussion I guess.