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Gold Identification

Gold purity marks.
Understanding 10K through 24K.

A complete guide to reading gold purity stamps on inherited jewelry — what each karat means, how European marks translate, and why the difference between solid gold, gold-filled, and gold-plated matters.

Understanding Karat

Gold purity marks and what they mean

The karat stamp on a piece of gold jewelry is the most important single mark on the piece. It establishes how much gold the piece contains, which determines its melt value and sets the floor for any sale price. Understanding the karat system, the European decimal system, and the many marks that look like gold but indicate something else is the starting point for evaluating any inherited gold jewelry.

The karat system

Karat measures gold purity on a 24-part scale. Pure gold is 24 karats — 24 out of 24 parts gold. Lower karat numbers indicate gold alloyed with other metals. 10K gold is 10 parts gold per 24 (41.7% gold); 14K is 14 parts per 24 (58.5%); 18K is 18 parts per 24 (75%); 22K is 22 parts per 24 (91.7%); 24K is essentially pure gold at 99.9%+. The karat number tells you exactly how much of the piece's weight is gold. Multiply the piece's weight by the karat percentage to get the gold content by weight.

10K — the minimum for US "gold" designation

10K is the lowest purity that can legally be sold as "gold" in the United States. Most 10K gold is used for inexpensive jewelry, class rings, and pieces where durability and low cost are priorities. The alloy metals (copper, silver, nickel, zinc) in 10K gold make the piece harder and more scratch-resistant than higher-karat gold but also give it a slightly different color — often a softer or more muted yellow than 14K.

14K — the American standard

14K has historically been the most common gold purity in American jewelry. It balances gold content with durability: enough gold for genuine value, enough alloy to resist everyday wear. Most American wedding bands, engagement rings, pendants, and fine chains are 14K. The mark "14K," "14KT," or "585" (the European equivalent) all indicate the same 58.5% gold content.

18K — the international standard for fine jewelry

18K gold (75% gold content) is the standard for most fine European jewelry and an increasing portion of the American high-end market. It has a richer, more saturated yellow color than 14K and holds up well for everyday wear in most designs. Signed designer jewelry is frequently 18K. The marks "18K," "18KT," or "750" all indicate the same 75% gold content.

22K and 24K — high-purity gold

22K (91.7% gold, "917") and 24K (pure gold, "999") are less common in Western jewelry because they are too soft for most everyday pieces. Rings and bracelets made of 22K or 24K gold scratch, bend, and lose their shape under ordinary wear. These higher purities are more common in Indian, Middle Eastern, and Asian jewelry traditions, where gold jewelry is often valued both as adornment and as portable wealth. Inherited 22K or 24K pieces typically come from those origins or from older estate collections where pure gold was preferred for specific pieces.

European decimal marks

Much of European and Asian gold jewelry uses three-digit decimal marks rather than karat numbers. The mark indicates parts gold per thousand. 375 equals 9K (37.5% gold, common in British jewelry). 585 equals 14K. 750 equals 18K. 917 equals 22K. 999 indicates pure 24K gold. The decimal system is more precise than karat numbers and directly shows the fineness. Both systems are legitimate; they are just different conventions for the same information.

Why gold is mixed with other metals

Pure 24K gold is too soft to hold a setting, resist scratching, or maintain a crisp edge. Alloying gold with other metals — copper, silver, nickel, palladium, zinc — increases hardness and changes color. Copper-heavy alloys produce rose gold; silver-and-nickel alloys produce white gold; higher copper-to-silver ratios yield warmer yellow tones. The alloy formula affects color and wearability but does not change the karat rating, which measures only the gold content.

Gold-filled and gold-plated marks

Not every "gold" mark means solid gold. Pieces marked GF (gold filled), 1/20 12K GF, 1/10 14K GF, or similar have a thick layer of gold mechanically bonded to a base metal core — the fraction indicates the proportion of gold by weight (1/20 means 5% gold). Gold-filled pieces have real but limited melt value. Pieces marked GP (gold plated), GE or HGE (gold electroplated), EP, or RGP have only a microscopically thin layer of gold over base metal — effectively no melt value. The difference between "14K" and "14K GF" on a piece is the difference between significant gold content and almost none.

Calculating melt value

Melt value depends on weight, karat, and the current spot price of gold. For a simple calculation: weigh the piece in grams, multiply by the karat percentage (14K = 0.585, 18K = 0.750), and multiply by the per-gram spot price. The result is the theoretical melt value before accounting for non-gold components (stones, clasps, backings). Scrap dealers typically pay 60–85% of spot, depending on the piece and market conditions. Stones and non-gold parts must be deducted from the piece's total weight before calculating.

Quick Reference

  • 10K / 417: 41.7% gold
  • 14K / 585: 58.5% gold
  • 18K / 750: 75% gold
  • 22K / 917: 91.7% gold
  • 24K / 999: 99.9%+ gold
  • GF: Gold filled (thin gold on base)
  • GP, GE, HGE, EP: Gold plated, minimal gold

Photo Tip

Photograph the karat stamp clearly — use macro mode or a magnifier. Look for additional letters next to the number: "GF," "GP," "GE," and "RGP" change the meaning entirely. A "14K" alone means solid gold; "14K GF" means gold filled. Record the weight in grams if you have a scale, since weight is needed to calculate melt value.

An Honest Take

What usually isn't valuable

Marks that look like gold but indicate little or no gold content.

Gold-plated (GP, GE, HGE, EP)

Marks indicating gold plating mean the piece has a microscopically thin layer of gold over a base metal core. The gold content is too small to have meaningful melt value — often measured in microns. Gold-plated jewelry sells based on design appeal alone, and that market is modest. No matter how much gold-plated jewelry you inherit, the combined melt value is effectively zero.

Gold-filled (GF, 1/20 GF)

Gold-filled pieces have more gold than plated pieces — the mark indicates a proportion by weight, typically 1/20 or 1/10 of the total weight — but it is still a small fraction of solid gold. A 20-gram gold-filled bracelet marked "1/20 14K GF" contains about 1 gram of 14K gold. Melt value exists but is modest. These pieces are sometimes worth more intact as wearable jewelry than as scrap.

Unmarked yellow metal jewelry

Jewelry with a gold color but no karat stamp is difficult to evaluate. Some early handmade gold pieces were never stamped, but most unmarked yellow-metal jewelry in estates is costume or gold-plated. Without a mark, buyers are cautious. Unmarked pieces typically need specialist in-person evaluation and acid testing to confirm the metal — and most fail the test.

Rolled gold plate (RGP)

Rolled gold plate is similar to gold-filled but often with thinner gold layers. RGP-marked pieces were common in 20th-century American jewelry, especially watch cases and pocket watch chains. The gold content is modest, and the intact design is usually worth more than the scrap value. For most RGP pieces, melt is not the right approach; condition and original use drive the modest market value.

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Common Questions

Frequently asked about gold purity marks

Karat measures the purity of gold on a 24-part scale, where 24K is pure gold. 10K is 10 parts gold out of 24, or 41.7% pure. 14K is 14 of 24, or 58.5%. 18K is 18 of 24, or 75%. 22K is 22 of 24, or 91.7%. 24K is 99.9%+ pure gold. The higher the karat, the more gold by weight, and the higher the melt value per gram. Gold is mixed with other metals (copper, silver, nickel, palladium) for durability — pure 24K gold is too soft for most practical jewelry use.
European jewelry typically uses three-digit decimal marks indicating parts gold per thousand. 375 means 37.5% gold, equivalent to 9K. 585 is 58.5%, equivalent to 14K. 750 is 75%, equivalent to 18K. 917 is 91.7%, equivalent to 22K. 999 is pure gold. These marks are common on German, Italian, French, and other European jewelry. The marks are not country-specific: a 750 stamp means 18K gold regardless of where the piece was made.
Solid gold is gold throughout, at the karat stamped (10K, 14K, 18K, etc.). Gold-filled jewelry (marked GF, 1/20 12K GF, or similar) consists of a thick layer of gold mechanically bonded to a base metal core — typically 5% gold by weight. Gold-plated jewelry (marked GP, GE, HGE, EP, RGP) has only a microscopically thin layer of gold over base metal, often measured in microns. Solid gold holds melt value; gold-filled has minor melt value; gold-plated has effectively no melt value. All three can look identical until you read the marks.
Multiply the weight of the piece by the karat percentage, then by the current spot price of gold. For example: a 20-gram 14K gold ring contains 20 × 0.585 = 11.7 grams of pure gold. Multiply by the spot price (in grams) to get the raw melt value. Scrap dealers pay below spot, typically 60–85%, depending on the piece and the current market. Stones and non-gold components must be deducted first. A specialist can provide a realistic melt estimate from photos and weights.
Pure and near-pure gold is too soft for most Western jewelry designs — rings and bracelets in 22K and 24K scratch, dent, and bend easily under everyday wear. American jewelry has historically favored 14K as a balance of gold content and durability. 22K and 24K gold jewelry is more common in Indian, Middle Eastern, and Asian markets, where gold jewelry traditions emphasize purity and gold-as-wealth rather than hard-wearing everyday jewelry. Inherited 22K or 24K pieces often come from those origins.
Higher karat means more gold by weight, so higher melt value per gram. But the total value of a piece also depends on the weight, the maker, the design, and any stones. A heavy 14K gold bracelet can be worth more than a light 18K one, even though the 18K has higher gold content per gram. Signed designer pieces can sell for many times melt value regardless of karat. Always consider total gold content, craftsmanship, maker, and design — not just the karat stamp — when estimating value.