The percentage of gold in a piece of jewellery is measured in carat units of 24, with 24-karats being pure gold. If the item is 10-karat gold, it means the piece has 10 parts gold to 14 parts alloy. Similarly for 14- carat gold, the piece is 14 per cent gold to 10 per cent alloy. The carat weight determines both the strength of the item and its cost: the lower the carat weight, the greater percentage of alloy, and the stronger the item. Lower carat weights are also less expensive. Comparison shoppers will want to be able to tell the difference.
Look for the stamp mark on the piece of jewellery. Read the marks as follows (European markings are in parentheses):
24 Carat = pure gold
18 Carat = 75% pure gold (750)
14 Carat = 58.3% pure gold (583)
12 Carat = 50% gold
10 Carat = 41.7% gold (417)
Examine the colour of the gold. Pure gold is often a deeper colour, but with lower carat weights, colour can be deceiving because the hue of the alloy can vary. A 14-karat ring in one store may look more yellow than one in another store, stamped with the same 14-karat marking.
Ask the jeweller. Your salesclerk should be able to help you determine the carat weight of a piece of jewellery, and may have a magnifier to help read the stamp. If not, ask if a jeweller is on the premises to help.
The minimum carat weight for gold that is permitted internationally is 9 carats. Its stamp will read 375 or 9.375. 24-karat gold is sometimes stamped 9.99 or .999 which refers to an industry term "three nines fine." Carat weight is different from the carat designation used for gemstones.