Items you will need
- Gram scale
- Jeweler's loop — a strong magnifying glass
The karat system was developed to measure purity in gold. Pure gold is 24k gold. Most of the old U.S. gold coins were 22k — or 91.66 percent gold on a 24k scale. Gold that is 75 percent pure is 18k and that which is 58.33 percent pure is 14k.
When buying or selling gold, the percentage of gold is an important number to keep in mind. Another number to know is the spot price of gold in dollars per ounce, which as of the date of publication was $1,044. The spot price of gold changes from day to day and even minute to minute. The third figure to remember is 31.1 — the number of grams in an ounce of gold.
Suppose you have nine 14k gold rings with a combined weight of 44 grams. To determine the value of the gold, first determine how many ounces of gold you really have. Divide 44 grams of 14k gold by 31.1 = 1.419 ounces of 14k gold. This gold is only 58.33 percent pure. Multiply the number of ounces by the percent gold: 1.419 ounces x 0.5833 = 0.827 ounces of pure gold).
Multiply the ounces of pure gold by the spot price of gold: 0.827 x $1,044 = $863.39. The result, $861.56, is the value of the gold in the nine rings.
Sometimes gold purity is marked in decimals, as 0.750 = 18k gold. Gold jewelry often includes a premium over spot due to its artistry of manufacture. Keep the spot price of gold in mind and compare the price asked with the spot price of gold when making an offer on any gold or gold jewelry.
Dividing the spot price of gold by 31.1 will give you a spot price per gram that you may quickly multiply by the number of grams in any piece of jewelry for a ball park value.