This is a favorite of scam gold buyers. They will weigh your gold out of sight and give you a false weight. You must see the scale. Some gold buyers have been known to weigh in pennyweights and tell you the pennyweight number was grams. So a 4.6 gram necklace would be 2.96 pennyweight. If you were unaware of the gram weight you just were cheated out of 1.6 grams of gold.