Im pretty sure its from the torch flame when they heat up the gold to wrap it around the bar. Try lighting a piece of gold with a lighter it will turn black but you can just wipe/polish it off
Almost every jewellry store in every mall here in vancouver has 10k sometimes 14k nothing more and they got rape prices. really only place I can find decent 14k-18k is in pawn shops
Every chain/bracelet on his site is $100 because its just a sample site. He does not use that site at the moment if you want real accurate prices hit him up on his instagram reysgoldandcash hes got his # on there you can text/call aswell.