A tiny stamp on the inside of a ring or the edge of a bar can change the conversation from pretty metal to measurable gold. For buyers and sellers in Tualatin, learning to read karat marks, fineness numbers, and mint marks is the fastest way to separate solid gold, plated fashion jewelry, and investment bullion.

This guide is a field manual for hallmarks educational, not a substitute for testing at the counter. Soft-touch note: marks help, but fakes and worn stamps exist; reputable shops verify with weight and analysis tools.

Local Coin Company buys and sells gold jewelry, dental gold, and gold bullion at 19354 SW Boones Ferry Rd., Tualatin, OR 97062. Hours MondayFriday 8 AM4 PM, Saturday 8 AM3 PM; appointments have priority. Call 503-855-5255. See current bullion listings on the gold page.

Karat: the twenty-four-part purity scale

Karat (often spelled carat in international jewellery writing) measures how many parts out of twenty-four are pure gold. The World Gold Councils jewellery purity overview explains the common framework:

• 24k essentially pure gold (commercially often refined to .999 or .9999)
• 22k about 91.7% gold
• 18k 75% gold
• 14k about 58.3% gold (very common in U.S. jewelry)
• 10k about 41.7% gold

Lower karat alloys add other metals for strength and color copper for rose tones, palladium or silver-family metals for white gold looks, and so on. Color alone does not prove purity.

Fineness stamps: the parts-per-thousand language

Millesimal fineness marks state gold content in parts per thousand. Common jewelry and bullion marks include:

• 999 / 999.9 near-pure / investment-grade fine gold
• 916 / 917 roughly 22k territory
• 750 18k
• 585 / 583 14k range (585 is widely used even though 14/24 is mathematically ~583)
• 417 10k range
• 375 9k (seen more often in some markets outside the U.S.)

World Gold Council materials note that manufacturers often mark 14k as 585 and that pure gold in practice is refined to high three-nines or four-nines levels rather than a theoretical 1000.

What U.S. consumer guidance says about quality marks

The FTCs consumer advice on buying gold jewelry emphasizes reading the karat quality mark and looking nearby for the name or U.S. registered trademark of the company standing behind the mark. A karat stamp without a makers mark is a yellow flag for careful buyers.

FTC guidance also clarifies plating language you will see in estate lots:

• Gold filled / gold overlay / rolled gold plate mechanically applied karat-gold layers over base metal (with thickness/fraction rules in industry guides)
• Gold electroplate electrolytic gold layer meeting described minimums
• Gold flashed / washed very thin coatings that wear faster
• Vermeil sterling silver base with a gold coating/plating (a special category)

Solid gold in FTC consumer language means the item is not hollow and it should still carry a karat mark telling you the alloy quality.

Mint marks and bullion hallmarks: a different codebook

Investment coins add mint identity and legal-tender legends. Examples that matter locally:

• American Gold Eagles: U.S. Mint materials describe them as 22-karat gold (~91.67% gold) with alloy for durability, containing the stated fine-gold weight in 1 oz, oz, oz, and oz sizes. Bullion Eagles are government-guaranteed for weight, content, and purity.
• American Gold Buffalos: marketed as .9999 fine 24-karat gold bullion coins.
• Canadian Maple Leafs and other sovereign issues: typically high-fineness gold with clear weight and purity inscriptions.

Local Coin Companys gold page lists American Gold Eagles (multiple sizes), Maple Leafs, Buffalos, Kangaroos, Philharmonics, Krugerrands, and gold bars when available the hallmarks and inscriptions on those products are designed for quick recognition.

Jewelry mint-style stamps (makers marks) are not the same as U.S. Mint mint marks on coins (P, D, S, W, and others on various U.S. issues). Coin mint marks help identify where a coin was struck and can matter enormously for collector dates; jewelry makers marks help attribute who stands behind a karat claim.

A Tualatin counter workflow for reading marks

1. Find the stamp with good light and magnification.
2. Translate karat or fineness into an expected gold percentage.
3. Note plating words that mean the piece is not karat-gold throughout.
4. Weigh only the gold-bearing parts after stones and non-gold components are understood.
5. Verify with testing marks are a hypothesis, not a final assay.

Related reading: Scrap Gold vs Bullion and counterfeit awareness in Fake Gold and Silver Coins. Soft-touch: live spot drives melt math; confirm current metal markets rather than memorizing a screenshot.

Common mix-ups that cost people money

• Assuming yellow color equals high karat
• Reading GP, GEP, or HGE as solid gold
• Confusing gold-filled jewelry with 14k solid
• Thinking a Gold Eagle is only 22k so it has less than an ounce of gold U.S. Mint specs call for the stated fine-gold content; the alloy makes the coin slightly heavier overall
• Ignoring makers marks on jewelry purchases

Bottom line for local buyers

Hallmarks are a compact map: karat and fineness tell purity, plating language warns about coatings, and mint marks or bullion inscriptions identify sovereign products. Learn the map, then still verify at a trusted counter.

Bring marked and unmarked pieces to Local Coin Company in Tualatin for a side-by-side read. Shoppers from Tualatin, Tigard, Beaverton, Lake Oswego, and greater Portland get clearer offers when karat math and bullion recognition are handled as separate, explicit steps.

Educational disclaimer: This article is general information about gold hallmarks, karat, fineness, and mint marks. It is not personal financial, tax, legal, or appraisal advice. Specifications cited from World Gold Council, FTC consumer materials, and U.S. Mint program descriptions can be updated; confirm on those primary pages. Spot prices move. Local Coin Company does not provide tax advice.