Karat content is determined by acid tests. Then the gold is weighed and the actual gold content is calculated. That day’s New York gold price is used to determine the price that will be paid. Most jewelers use grams for these calculations, but some gold buyers use pennyweights (DWT) instead. There are 20 pennyweights per Troy ounce, rather than 31.1 grams per Troy ounce.
Some dealers will quote you a price per pennyweight without telling you it is being quoted in pennyweights. The price will sound higher and this can be used to deceive you. For example, if one dealer offers you $20 per unit of weight and another offers you $15, which one would you take? If your 14k gold weighed, for example, 1 Troy ounce, the first offer of $20, in pennyweights, would net you $400. The second offer of $15, in grams, would net you $466. So when you get a quote, be sure to ask if the quote is in grams or pennyweights. Compare other offers using the same unit of measurement.