What Karatage Means?
For example, when buying gold jewelry, look for 14k, 18k or 22k markings on every piece. Most gold sold in the U.S. is 14-karat, meaning 14/24ths gold, or 565. Eighteen-karat gold, a standard in Europe, is 18/24ths gold, or 750. It may be marked 18k or 750.
How Platinum Marks Differ
Platinum has a different hallmark, usually 850, 900 or 950. The stamp will read 850 Plat, 900 Pt or 950 Plat. or some variation of these. That means each piece is between 850 and 950 parts pure platinum, 50 to 150 parts alloy.
What to Look for on Sterling Jewelry
Sterling silver jewelry is marked .925. That means the piece is 925 parts silver, 75 parts alloy. Silver, like gold, is relatively soft in its pure state and uses alloys to strengthen it for jewelry.
Why the Trademark Is Important
The other designation you should look for is the manufacturer's trademark. A mark registered with the U.S. patent office, it can appear as a symbol, a number or even a name. Foreign producers, particularly Italians, use a combination number and letter code to indicate the company's identification and the city in which the piece was made. Other manufacturers, particularly brand-name designers, often engrave the back of the piece with their name or company logo. These designations are important to you because they assure you of the metal content and standard of a piece of jewelry. Further, in the case of designer jewelry, the name or trademark is of additional significance for appraisal or insurance purposes. Most other products you buy are backed up with warranties and labeled with serial numbers. Consider the hallmarks and trademarks on your jewelry as the same types of guarantees.
Graduate Gemologist, GIA
Certified Appraiser