Maybe you have some jewelry sitting in your jewelry box, collecting dust. You've had it since you were young, or maybe you inherited it. How can you figure out the value of these pieces?
The easiest thing to do is to look for a stamp. You'll be looking for these stamps inside rings or on the backs of earrings or pendants.
Gold and Platinum Jewelry Stamps
10K - may also be stamped as 417, which means that 41.7% of the alloy is pure gold
14K - may also be stamped as 585, which means that 58.5% of the alloy is pure gold
14KP - the P means "plumb" (a term that is no longer is common use), this signifies the same alloy as a 14K stamp
18K - may also be stamped as 750, which means that 75% of the alloy is pure gold
PLAT - which may also be stamped as 900 or 950
Occasionally you may run into a piece that is not stamped but actually is made of gold. This is an unusual case, but is most likely for pieces made by local artists, or for pieces that were sized and had the stamp removed in the sizing process. If you're unable to find a stamp, you can opt to have your jewelry checked with an acid assay test or x-ray florescence test to determine the alloy.
Gold-filled and Gold Plated Jewelry Stamps
Gold-filled means there's a thin gold outer surface to your jewelry, and it is filled with a base metal. A gold-filled piece is more valuable that a gold plated/vermeil piece because there is more gold present, but it will still be significantly less valuable than a solid gold piece.
14K GF - means gold-filled
14K GP - means gold plated
14K HGE - means heavy gold electroplate
14K EGP - means electric gold plate
14K 1/20 - means that the piece is gold plated, with at least 5% of the total weight being 14K gold
Silver Jewelry Stamps
STERLING, STER, or 925 all mean sterling silver
Tools for Stamping Rings
Jewelry is quality-stamped by the maker using a heavy steel stamp. Here's an example of a few ring stamps. You can tell that they're made especially for stamping rings because of the bent shank. That curve leaves room for the ring itself, while your jeweler stamps the inside of the ring.
Ring stamps are often used in conjunction with brass ring stamping anvils. These ring stamping anvils have curved surfaces, and different shaped hollows to fit different rings. Stamping rings against a form that fits the ring means there will be less deformation during the stamping process.
Sneaky Places Stamps Might Be Hiding
Make sure to look on the tongues of opened necklace clasps and also on earring posts. Also, keep in mind that pendants may not always be made of the same metal as their chain. It's best to check the stamp on each!