Knowing the properties of your metal can help you understand the prices being offered for your old jewelry.
Most rings are either 10 karat (41.7% pure gold) or 14 karat (58.3% pure gold) or 18 karat (75.0% pure gold). 100% pure gold is 24 karat. When you are selling gold, the refinery is only paying you for the pure gold not the alloy. The alloy are other metals that are mixed with gold to make it more wearable. Also the original jewelry has the labor and profit which you lose at scrap prices.