Precious metals are required by law to bear a stamp indicating quality and content. Most of us recognize the familiar “10K” and “14kt” – but there are many common markings with less obvious meaning. Here’s a cheat sheet of frequently seen jewelry markings with brief explanations. A little bit of knowledge goes a long way in making you a more educated buyer!
Gold used in jewelry is mixed with several metals to make it more durable. The word “karat” indicates the amount of gold in an alloy, on a scale of 1 to 24. This means that 18 karat gold is 18 parts gold to 6 parts other metals, or 75% gold. (Read more about the making of gold jewelry)
- 10K (or “10kt”) = 41.7% gold content
- 14K = 58.5%
- 18K = 75%
- 22K = 91.67%
Gold is mixed with metals such as copper, silver, zinc, or palladium. Depending on the alloy, gold can take on many colors beside the more popular yellow, white, and rose/pink. Gold alloys that contain nickel – a cheaper alternative – are the common culprit for green marks left on the skin.
White gold is usually coated with rhodium, a precious metal with a brilliant white finish. White gold without rhodium finish, or with the rhodium worn off, will have a slightly dull yellowish patina.
Did you know…
White gold can easily be re-finished by a bench jeweler. A new coat of rhodium will make it look like new!
Jewelry that has gold only on the surface can be gold plated, gold filled, or electroplated. “Gold filled” indicates a heavy layer of gold at least 12 karat that makes up a minimum of 1/20 of the jewelry’s weight.
You can recognize this kind of jewelry by the following markings:
- 1/10 or 1/20 GF = “gold filled,” usually along with a karat stamp
- RGF = “rolled gold filled”
- GP = “gold plate”
- GEP = “gold electroplate”
- HGE = “heavy gold electroplate”
Vermeil is a gold surface over sterling silver. It will include “925,” the sterling stamp (see below).
Silver, like gold, is mixed with an alloy when made into jewelry. Sterling is a quality standard requiring 92.5% silver content, which is why the most widespread sterling marking is simply “925.”
Silver of a lower grade alloy, such as coin silver, may be marked “900” (i.e., 90.0% silver).
Did you know…
Each country has a different sterling standard – the minimum silver content to qualify as fine jewelry. Various hallmarks, as well as maker’s marks, have been used throughout history and can help track the origin of silver jewelry.
Hallmarks on Old Jewelry
Platinum is a very heavy, dense white metal that is usually in an alloy with earth metals such as iridium or ruthenium. Platinum jewelry is most often marked 900 or 950.
More often than not, jewelry that is not stamped contains no significant amounts of precious metals – i.e., fashion or costume. Keep in mind that while these guidelines are a good rule of thumb, the presence or absence of a jewelry marking is not necessarily a guarantee. A piece of fine jewelry may have had the stamp worn off over the years, while a piece stamped “14kt” may not be what it claims. If you have any doubts, a trusted jeweler can test the metal to determine its quality.