Reading the hallmark: a connoisseur's guide to precious metal markings.
June 11, 2026A hallmark is the most concise piece of writing on any piece of jewelry. Stamped in a space rarely larger than two millimeters, it tells the wearer everything essential about the metal in their hand: what it is, how pure it is, and in many cases, where it was made. To the connoisseur, reading a hallmark is the first act of evaluating a piece. To the new collector, it is the most reliable way to verify what they are about to wear.
This guide walks through the system of hallmarks used on precious metal jewelry today, from the karat markings on gold to the millesimal stamps on platinum, with attention to the markings that signal pure precious metal and those that indicate plating, filling, or alloy. Understanding the system is part of how a collection is built with intention, and it is the foundation for distinguishing pure 24k gold and pure platinum from the alternatives.
What a hallmark is and where to find it.
A hallmark is a small stamped marking applied to a piece of jewelry to indicate the precious metal content of the piece. The practice dates back over seven centuries in Europe, where the earliest formal hallmarking system was established in England in 1300 by King Edward I as a measure to protect buyers from fraudulent metal. Since then, the system has spread across nearly every major jewelry-producing region, with each developing its own conventions while sharing the same fundamental purpose.
The location of a hallmark depends on the type of piece. On rings, it is most often found on the inner band. On chains and bracelets, it appears on the clasp or on a small tag near the clasp. On earrings, it is stamped on the post or the back. On pendants, the marking is usually placed on the bail or on the back of the piece.
Hallmarks are small by design, often less than two millimeters in height, which is why a jeweler's loupe or the magnification on a phone camera is generally needed to read them clearly. A clean, well-applied hallmark is itself a sign of a piece made with care.
Karat markings: the system of gold purity.
The karat system divides gold into 24 parts and uses those parts to indicate purity. A piece marked 24k contains 24 parts gold out of 24, or approximately 99.9 percent pure gold. As the karat number decreases, the proportion of gold in the alloy decreases correspondingly. The most common karat markings on gold jewelry are:
- 24k or 999 indicates pure gold, with approximately 99.9 percent gold content. This is the highest purity used in jewelry.
- 22k or 916 indicates 91.6 percent gold, common in traditional South Asian jewelry and high-purity gold pieces from Middle Eastern markets.
- 18k or 750 indicates 75 percent gold, the most common karat in European fine jewelry.
- 14k or 585 indicates 58.5 percent gold, common in American fine jewelry.
- 10k or 417 indicates 41.7 percent gold, the lowest karat that can legally be sold as gold jewelry in the United States.
The numeric markings (999, 916, 750, 585, 417) follow the millesimal system, which expresses purity in parts per thousand. This system is used widely in Europe and has become increasingly standard internationally. A piece may carry either the karat marking or the millesimal marking, or both.
A marking followed by the letter P, such as 18KP, denotes plumb gold, meaning the purity is exact rather than within a permitted tolerance.
Platinum hallmarks and what they mean.
Platinum is hallmarked differently from gold, with markings that reflect the metal's distinct characteristics. The standard platinum markings are:
- PT999 or 999 Pt indicates pure platinum, with approximately 99.9 percent platinum content. This is the highest purity used in jewelry.
- 950 Pt or PT950 indicates 95 percent platinum, the most common purity in European and American platinum jewelry.
- 900 Pt indicates 90 percent platinum, sometimes used in heavier or more sculptural pieces.
- 850 Pt indicates 85 percent platinum, the lowest commonly accepted purity for platinum jewelry.
Unlike gold, where lower-purity alloys are widely used and visually similar to pure metal, platinum tends to be sold in higher purities across the board. The cool tone, density, and finish of platinum read consistently across these purity levels, but the highest-quality pieces are made in PT999, where the metal carries its full character within the piece.
Markings that indicate plating, filling, or alloy.
A separate category of hallmarks signals that a piece is not solid precious metal. Recognizing these markings is essential, particularly for any wearer building a collection intended to be worn continuously or kept across generations.
GP stands for gold-plated, indicating that the piece is made of a base metal coated with a thin layer of gold.
GEP stands for gold electroplated, the same process applied through electrolysis.
HGE or HGP refers to heavy gold electroplate, a slightly thicker layer of gold than standard plating but still a surface coating rather than solid metal.
RGP stands for rolled gold plate, an older method of bonding gold to a base metal through mechanical pressure.
GF stands for gold-filled, where a thicker layer of gold is bonded to a base metal core through heat and pressure. The gold layer in a gold-filled piece must comprise at least 5 percent of the total weight, making it more durable than plated alternatives, but still not solid gold.
For platinum, similar plated markings exist, though they are less common. A platinum-plated piece is most often marked PP or simply not hallmarked at all, since the practice is far less standardized than gold plating.
A stamp such as 18K GP does not mean the piece is 18k gold. It means the piece is plated with 18k gold over a base metal. The distinction is critical for understanding what the piece actually is.
What the absence of a hallmark means.
Not every piece of jewelry carries a hallmark. Older pieces, particularly those made before formal hallmarking became standard in their region, may have no markings at all. Some custom pieces and pieces from regions with less formalized hallmarking systems may also be unmarked, even when they are made from pure precious metal.
The absence of a hallmark, however, is rarely a good sign on a modern piece. Reputable fine jewelry today is almost always hallmarked. When a piece sold as gold or platinum carries no hallmark and no documentation, the wearer is relying entirely on the seller's word. Professional testing, such as XRF analysis, can verify the metal content of an unmarked piece without damaging it, and is the only reliable way to confirm what an unmarked piece actually is.
For the connoisseur, the presence of a clear, well-applied hallmark is part of how a piece is evaluated. A hallmark that is sharp, complete, and consistent with the piece's stated purity is itself a sign of a maker who works with intention.
What hallmarks alone cannot tell you.
A hallmark indicates the metal content of a piece but cannot guarantee everything about it. Hallmarks can be counterfeited, particularly on pieces sold outside of established markets. The marking also tells the wearer about the metal, not about the craftsmanship, the design, or the long-term wearability of the piece.
This is why a hallmark is best understood as the beginning of evaluating a piece rather than the end. The wearer should also consider the weight (pure precious metals are denser than alloys and feel heavier in the hand for their size), the color (24k gold has a deep, warm yellow that lower-karat alloys cannot replicate), the finish (pure metal does not have the surface unevenness of plating), and the provenance (a piece from a maker who is transparent about their material is more reliable than one from an unknown source).
Hallmarks at Menē.
Every Menē piece is stamped with the marking that confirms its purity. Pieces in 24k gold carry the 24k hallmark, indicating the highest level of gold purity used in jewelry. Pieces in pure platinum carry the PT999 hallmark, indicating the same standard for platinum.
There is no plating, no surface treatment, and no alloy diluting the metal in any Menē piece. The hallmark is a statement of what the piece actually is: pure precious metal, throughout.
Explore the Menē collection in 24k gold and pure platinum and discover pieces shaped from precious metals in their purest form.
