What is karat?
Short answer: A karat is one twenty-fourth part of pure gold, so 24 karat is pure gold and 18 karat is 75% gold.
Common stamps are 22K (91.6%), 18K (75%), 14K (58.5%) and 10K (41.7%). The same figures are often stamped as fineness numbers, such as 916, 750, 585 and 417.
Try it: Gold melt value calculator