What is a gold hallmark? It’s a mark that is stamped on gold jewelry to indicate its purity—and value. You may have noticed them while admiring a beautiful piece of gold jewelry; usually, they are small numbers, letters or symbols discreetly hidden on the jewel’s underside or clasp. The gold hallmark can offer important clues about the piece, such as where it’s from, its metal composition, and even how much it’s worth. This info will be especially helpful to you if you’ve inherited some gold jewels and want to authenticate them, especially if your plan is to resell or consign them. It will also come in handy when you are shopping at an estate jewelry shop or flea market and want to be sure you’re getting a good deal.
In the guide below, we’ll explore in further detail the history of gold hallmarking, as well as the different types of gold jewelry stamps and what they mean. Once you gain this knowledge, you’ll be a gold hallmarking pro in no time.
How To Locate Jewelry Hallmarks
- First, you’ll need a magnifying glass or a jeweler’s loupe.
- On rings – the hallmark is usually stamped on the inside of the band
- On chains and necklaces – the hallmark is located near or on the clasp
- On bracelets – the hallmark is near the clasp (if present) or on the inside of the band
- On earrings – the hallmark is typically stamped on the post or back of the earring
A Brief History of Gold Hallmarks
The origins of hallmarking gold jewelry can be traced back to 13th century England when King Edward I introduced a statute where it was decreed that no piece of gold would be offered for public sale without it first being assayed (tested) and marked with the symbol of a leopard’s head (roar!).
As one of the earliest forms of consumer protection, hallmarking set the standard for quality control processes in jewelry-making all over the world. Today, different countries have their own requirements and distinctive marks for hallmarking gold jewelry. In the U.K., for example, gold jewelry (over certain weights) must be hallmarked in one of the four assay offices located in London, Birmingham, Sheffield, or Edinburgh before it can be sold. In the U.S., it is required by the National Gold and Silver Marking Act of 1906, that gold jewelry be marked with a karat stamp denoting its purity.
Understanding Gold Purity: A Chemistry Lesson
One of the most important factors you should consider before buying gold jewelry is how pure it is. A gold jewel’s purity is directly related to how much it’s worth. You may be surprised to learn that gold jewelry is rarely 100% pure gold. This is because gold on its own is too soft and brittle to be used for jewelry making. To make gold jewelry more durable and less prone to scratches and dents, gold is often alloyed (mixed) with other metals, such as silver, copper, zinc, or palladium.
There are two primary ways to measure the purity of gold: the karatage system and the millesimal fineness scale. Each denotes the ratio of pure gold to other metals present in the piece in its own way. The karatage system is used in the U.S. and Canada, whereas the millesimal fineness scale is favored internationally.
The Gold Karat System
A “karat” (not to be confused with a “carat” which is used for measuring a gemstone’s weight) is a unit that measures gold purity in fractions of 24. The number of karats refers to the content of the piece that is pure gold. The higher the number of karats, the purer the gold. 24 karats are the purest (i.e., 24 out of 24 parts are gold).
How to Read Gold Karat Marks
A gold karat mark includes a number followed by a K, KT, or Kt. Here are a few common gold karat stamps:
9K (or 9KT or 9Kt)
A jewelry item stamped with a “9K” means that out of a total of 24 parts, 9 parts of the piece are gold, and 15 parts are made up of other metals. To convert to a percentage, divide 9 parts by 24 which is 0.375 or 37.5% gold. The remaining 62.5% are alloy metals. 9k gold is the lowest of all gold karats and does not have the same deep yellow color as higher-karat gold. However, it may be a good option if you’re on a tight budget.
10K (or 10KT or 10Kt)
A “10K” stamp indicates that 10 parts of the piece are gold, and 14 parts are made up of other metals. In other words, the piece is 41.7% gold and 58.3% alloy. 10k gold jewelry is pale yellow in color and a good choice if you are looking for something affordable and durable enough for everyday wear.
14K (or 14KT or 14Kt)
A “14K” stamp indicates that the piece contains 14 parts pure gold and 10 parts other metals or is 58.3% gold and 41.7% alloy. When buying 14k gold jewelry, you have three options: white gold, rose gold, and yellow gold. 14k gold is a popular choice for engagement rings and wedding bands due to its intense color and resistance to wear and tear.
18K (or 18KT or 18Kt)
An “18K” stamp indicates that the piece contains 18 parts pure gold and 6 parts other metals, or is 75% gold and 25% alloy. 18k gold is considered the luxury standard in the U.S., particularly when it comes to wedding jewelry.
24K (or 24KT or 24Kt)
A “24K” stamp indicates that the piece is 99.9% gold. 24k gold has a beautiful and rich appearance; however, because it doesn’t contain alloys, it’s softer and thus, easier to dent.
Look for Letter Markings Next to the Karat Stamp
Sometimes a karat stamp will be followed by other letters such as P, GP, GF, GE or GEP, HGE, or RGP. Let’s decode their meanings below.
- P: A “P” mark indicates the piece is plumb, meaning the gold purity is exact.
- Example: ’10KP’ is exactly 41.7% gold.
- GP: A “GP” mark stands for “gold-plated” meaning the jewelry is comprised of a thin layer of gold (0.05%) bonded to another base metal (usually copper, silver, or brass). Gold-plated jewelry is generally low quality, tarnishes easily, and can be harsh on sensitive skin.
- Example: An “18K GP” stamp does not mean the piece is 18k gold but rather it is made of a base metal and plated with 18k gold.
- RG or RGP: An “RG” or “RGP” mark stands for “rolled gold” or “rolled gold plate.” Rolled gold contains 100 times more gold than average gold plates; therefore, it is of higher quality than a jewelry item labeled as “gold plated.”
- GF: A” GF” mark stands for “gold-filled.” Gold-filled jewelry has a thicker layer of gold (at least 5%) than GP jewelry and is more durable and hypoallergenic. Common markings include the karat number and GF, or a fraction followed by the karat and GF.
- Example: “10K GF” or “1/20 10K GF” (1/20 means that 5% of the gold is 10 karats)
- GE or GEP: A “GE” or “GEP” mark stands for “gold electroplated” meaning that the jewelry is plated with gold via electroplating – a process in which a thin layer of gold is applied to base metal using an electric current.
- HGE: “HGE” stands for “heavy gold electroplate” or “hard gold electroplate” meaning that the piece is gold-plated with a slightly thicker layer than a GP or GE piece.
The Millesimal Fineness Scale
Unlike the karat system that tells you the gold metal content expressed in parts per 24, the millesimal fineness scale expresses purity in parts per 1000. A fineness mark is stamped as a three-digit number that indicates the percentage of gold in the item.
What Does a 375 Gold Jewelry Stamp Mean?
If a piece of gold has the hallmark “375,” it is 37.5% pure gold or 9k gold.
What Does a 417 Gold Jewelry Stamp Mean?
A “417” stamp on gold jewelry indicates the jewelry contains 41.7% pure gold or 10k gold.
What Does a 585 Gold Jewelry Stamp Mean?
“585” stamped on a piece of gold jewelry indicates the jewelry contains 58.3% pure gold or 14k.
What Does a 750 Gold Jewelry Stamp Mean?
A “750” marking indicates a piece of gold jewelry is made of 75% gold or 18k.
What Does a 916 Gold Jewelry Stamp Mean?
A “915” stamp means a piece is 91.6% gold or 22k.
What Does a 990 Gold Jewelry Stamp Mean?
A “990” marking on a piece of gold jewelry means it is 99.0% gold or 23k.
What Does a 999 Gold Jewelry Stamp Mean?
A “999” marking indicates a piece is 99.9% gold or 24k.
Jewelry Maker’s Mark
Aside from purity marks, gold jewelry may be stamped with a maker’s mark which identifies the designer or manufacturer of the piece. Also known as a trademark, a maker’s mark can be in the form of a brand logo/symbol, name, or initials. Think of it as a fashion label that lets you know it’s the real deal and not a knock-off. Examples include Tiffany & Co.’ or ‘T & Co.’ for Tiffany’s, and HW for Harry Winston. If there is a maker’s mark that you can’t immediately identify, definitely do some research and/or consult a jeweler—“signed” pieces (read: hallmarked) tend to be worth more than those that aren’t, even if the maker in question is not a household name.
What if Gold Jewelry Doesn’t Have a Stamp?
If you don’t see a hallmark on your gold jewelry, don’t panic. There can be many reasons why it might not be stamped, such as the hallmark could have worn away from normal wear and tear over time, it may be an older piece that didn’t need to be legally stamped, or it was made by an independent jewelry designer. Of course, there is also the possibility that the item is not actually gold. If you’re unsure about the authenticity of your gold piece, try these tests (or take it to a reputable jeweler to find out for sure). No matter what type of gold jewelry you own or hope to buy, protect your investment by obtaining personal jewelry insurance through Jewelers Mutual. It’s an affordable option that covers loss, damage, and mysterious disappearances. You can receive a jewelry insurance quote in just 30 seconds by clicking the button below.