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Want to know what those markings mean on your jewelry? In this article, we break down the difference between precious and base metals, as well as the different quality markings you'll find on gold, silver, and platinum.
Precious Metals are metals that are used in fine jewelry. More specifically, the main types of precious metals used in jewelry are: gold, platinum, and silver.
Base Metals are non-precious metals, or metals used for a variety of purposes and not primarily jewelry. These types of metals include copper, zinc, tin, nickel, lead, and iron. These metals are sometimes used as an alloy material alongside precious metals (more on this below), and they are often used in making costume jewelry, sometimes with a thin covering (or “plate”) of precious metal over the top.
When a piece of jewelry is made of precious metal, the piece will typically carry a stamp or quality marking indicated the type and purity of the metal.
In the remainder of this article, we’ll go over the different markings you’ll most likely come across with gold, silver, and platinum.
Gold’s fineness (purity) is based on a system of 24 parts, using the term “karat” or the abbreviation “k.”
24K gold is pure gold. Or 24 out 24 parts are pure gold. This may sound like “the best” there is and the option people should prize the most when it comes to fine jewelry. But the truth is that pure gold is actually relatively soft and doesn’t stand up well to the wear and tear that, for example, an engagement ring goes through every day.
18K gold is 18 parts gold out of 24, with the other parts being made of alloy metals to strengthen the gold for everyday wear as jewelry. 18K gold, particularly 18K yellow gold, has a deep and beautiful color.
Unfortunately, because of its higher gold content, it can sometimes have durability issues because of its relative softness. It may bend or scratch more easily than 14K gold. If a piece of jewelry is 18 karat gold, it will typically be stamped “18K”.
14K gold is 14 parts gold with 10 parts alloy metal. 14K is the most common gold purity used in jewelry and it the preferred level of purity for many manufacturers and jewelers because it offers both the beauty of gold as well as durability for everyday wear. If a piece of jewelry is 14 karat gold, it will typically be stamped “14K”.
10K gold is 10 parts gold with 14 parts alloy metal. Because 10K gold contains more alloy metals than gold, it’s generally regarded as cheap, poor quality, or “discount” gold.
The lower concentration of gold means the jewelry will be less expensive and possibly more durable depending on the alloy metals used. But it can also create to other issues like corrosion that discolors your skin. Gold itself does not corrode, but the alloy metals can. 10K gold has a high concentration of alloy materials that can be responsible for corrosion and/or an allergic reaction with your skin.
If a piece of jewelry is 10 karat gold, it will typically be stamped “10K”.
There are a few other markings you may come across in conjunction with a karat quality mark, such as: G.P., G.E.P., H.G.E., or G.F.
These stand, respectively, for “gold plate,” “gold electroplate,” “heavy gold electroplate,” and “gold filled.”
For example, a piece of jewelry stamped “18K G.P.” is not jewelry made of 18K gold, but rather it is made of base metal and plated with 18K gold.
Don’t confuse “karat” and “carat.”
“Karat” is a measurement of gold purity.
“Carat” is a measurement of weight in gemstones.
Silver is relatively simple when it comes to silver used in jewelry in the United States (this article will not cover silver markings on other products like silverware, or quality markings from other countries).
Silver quality is expressed as parts of pure silver out of 1,000. The “sterling standard” is 925/1000.
Sometimes you will hear sterling silver referred to as “925” or “925 sterling.”
So no more than 75 parts out of 1,000 can be alloy metal (copper) in sterling silver. As with gold, the copper helps harden the precious metal and improve its durability for everyday wear.
When it comes to markings on sterling silver, older pieces will generally be marked “sterling” or “sterling silver,” and newer pieces of jewelry are marked “925” or “925 sterling.”
Items that are silver plated (over base metal) cannot legally be called “sterling,” or bear a “silver” hallmark.
For jewelry to be called “silver” in the United States, the metal must be 925 parts silver out of 1000, or 92.5% silver.
Like silver, platinum’s fineness is measured out of parts per 1,000. Most platinum jewelry is marked either 900, 950, or 999.
In many ways, platinum is the ultimate precious metal for jewelry. It’s a strong, workable, durable metal. It is both beautiful stands up well to everyday wear and tear on its own, requiring fewer alloy metals. Because it requires fewer alloys, it’s less brittle than gold alloy and offers a more secure setting for the most valuable gemstones.
All platinum jewelry has a “hallmark” of quality, and it’s typically some combination of “PT” or “PLAT” and a number indicating the purity of the platinum (out of 1,000). Here are some of the common markings you may see (from source):
PLATINUM or PLAT
PT950
950PT
950PLAT
PT900
900PT
900PLAT
PT999
PT850
I hope this short guide was helpful for you in making sense of the quality markings (or “hallmarks”) that are present on nearly all jewelry.
Keep in mind that these markings can sometimes vary slightly, particularly with older pieces of jewelry or jewelry from other parts of the world.
If you ever have any doubt about the quality of your jewelry, consult a certified jewelry professional.
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