It’s very difficult to glance at a piece of jewelry and figure out exactly what it’s made of. A sterling silver pendant can be rhodium plated, a genuine piece of gold could be chemically tarnished, and many other circumstances could befall any jewelry and betray its true value. Luckily, we have a standard, rigorously enforced set of markings a piece of jewelry can bear. The most common markings are 10k, 14k, etc. An alternative to these markings take the form of 3 digit numbers. These markings represent how many parts out of 1,000 are pure gold in jewelry. They match up nicely with the markings representing 10k, 14k, etc. For example 417 denotes gold that is 41.7% pure or 10k gold. In addition to the karat notation, you might find a few pieces marked with a ‘KP’ for example 14KP. The ‘kp’ stands for karat plumb and that means the piece is guaranteed to be at least the noted purity. In the US, gold purity can be rounded up to the standard purities if the difference is at most 0.5 karats. So there’s a small chance something marked as 10k could actually only be 9.5 karats.
On the other hand, there are markings that indicate a piece of jewelry isn’t genuine gold. If you find HGE, GE, or GP on a piece of jewelry, it is gold electroplated. Respectively, they stand for Heavy Gold Electroplated, Gold Electroplated, and Gold Plated. The very outer layer is gold that’s been electrochemically bonded to a base metal. The total amount of gold in pieces marked as such is negligible and not worth processing on a single item basis. If you see an ‘RG’ stamp, it means the jewelry was created with rolled gold. It sounds like a fancy elaborate process to manufacture jewelry, but in essence, it is very similar to gold plated jewelry. Another mark you might see is GF which stands for Gold Filled. Gold filled jewelry is a little more nuanced than the plated jewelry. This specific hallmark will be preceded by a fraction such as 1/10 or 1/20 which details what portion of the total weight of the jewelry is genuine gold. For example, a ring stamped with ‘1/20 14kt GF’ means it is gold filled but 1/20th of the weight is 14k gold. While the gold content of an individual piece of gold filled jewelry is miniscule, it’s significantly greater than gold plated and larger refineries might be open to processing it if enough of it comes in.
Now onto markings for stuff that isn’t gold at all. The most common stamp you’ll see is probably 925. The 925 mark is used for sterling silver jewelry which is 92.5% pure silver. Sterling silver can also be marked simply with a ‘Sterling’ stamp. For a piece of silver to be sold as Sterling silver, it must be marked with either Sterling or 925. You might see silverware sets marked with ‘Silver’ or ‘Silversmiths’ but there’s no guarantee they’ll be Sterling silver. It is absolutely crucial that if you’re shopping for Sterling silver, you locate and verify the 925 or Sterling marking.
Next up is platinum and platinum jewelry can be marked in several ways. The easiest to distinguish stamps simply read Platinum, Plat, or Pt. Paired with the stamp indicating platinum will be a mark to indicate the purity of the platinum. Most often, you’ll see stamps reading 900 or 950 meaning the piece of jewelry is 90% or 95% pure platinum.
There are quite a few other hallmarks you’ll see on jewelry that aren’t detailed in the previous sections. If it’s some stamped numbers in a piece of diamond jewelry that don’t match up with those previously mentioned, there’s a chance the manufacturer marked the total carat weight on the item. To confirm this, you can consult any receipts that might have come with it or take it to a jeweler to count and measure the diamonds. A task like this is pretty simple so it should only take a few minutes and can be completed while you wait. And finally, there are maker’s marks. These are used to indicate who made the piece of jewelry. These are most often a set of letters but can be incredibly ornate like an eagle and lion standing on either side of the letter R on certain Reed & Barton silverware items. When in doubt, you can always perform a quick internet search to decipher the markings on jewelry and silverware.