When you look closely at your ring, necklace, or bracelet, you’ll usually see tiny numbers and letters stamped inside. These aren’t random—they’re a code that tells you:
- What metal it is
- How pure that metal is
- Who made it
- Sometimes where and when it was made
This guide will walk you through how to read those marks, with simple diagrams and examples you can compare to your own jewellery.
1. Where to Look for the Stamps
On most pieces, you’ll find stamps in places that aren’t easily visible when worn.
Common locations:
- Rings: Inside the band
- Necklaces/bracelets: On the clasp or a small near-clasp tag
- Earrings: On the post, back, or underside of the setting
- Pendants/charms: On the back or on the bail (the loop that attaches to the chain)
Simple Ring Diagram (Text-Based)
Imagine looking at the inside of your ring:
Outside of ring Inside of ring
________ ________
/ \ / \
| | | 14K |
\________/ \________/
^
Stamp is here
What you’re looking for will usually be very small. A magnifying glass or your phone’s camera (zoomed in and well lit) can be helpful.
2. The Most Important Numbers: Metal Purity
Most of the numbers you see are about metal purity — how much real gold, silver or platinum is in the piece.
2.1 Gold – Karats and Fineness Numbers
Gold is often marked in karats (K or KT) or fineness numbers (3-digit numbers like 585).
- Karats (K): Out of 24 parts
- 24K = pure gold
- 18K = 18 parts gold, 6 parts other metals
- 14K = 14 parts gold, 10 parts other metals
- Fineness numbers: Parts per thousand
- 999 = 99.9% pure
- 750 = 75.0% pure (≈ 18K)
- 585 = 58.5% pure (≈ 14K)
- 417 = 41.7% pure (≈ 10K)
Common Gold Stamps and Their Meaning
|
Stamp |
Meaning |
Purity approx. |
|
24K |
24 karat gold |
99.9% |
|
18K |
18 karat gold |
75% |
|
14K |
14 karat gold |
58.5% |
|
10K |
10 karat gold (US minimum) |
41.7% |
|
999 |
Fine gold |
99.9% |
|
750 |
18K gold |
75% |
|
585 |
14K gold |
58.5% |
|
417 |
10K gold |
41.7% |
Example:
If your ring is stamped 585, it’s 14K gold (58.5% pure), even if it doesn’t say “14K”.
3. Silver Stamps
Most genuine silver jewellery is sterling silver.
- Sterling silver = 92.5% silver + 7.5% other metals (usually copper)
Typical Silver Stamps
|
Stamp |
Meaning |
Purity |
|
925 |
Sterling silver |
92.5% |
|
STER |
Sterling silver |
92.5% |
|
STERLING |
Sterling silver |
92.5% |
|
800 |
Continental silver (Europe) |
80% |
|
999 |
Fine silver |
99.9% |
If you see 925, STER, or STERLING, that usually means it’s real silver (not just plated).
4. Platinum and Other Precious Metals
Platinum and palladium are often used in fine jewellery.
Platinum Stamps
|
Stamp |
Meaning |
Purity |
|
PLAT |
Platinum (usually ≥90%) |
Often 900–950 |
|
950 |
95% platinum |
95% |
|
900 |
90% platinum |
90% |
|
PT |
Platinum (short form) |
Varies, check context |
Palladium Stamps
|
Stamp |
Meaning |
|
PD |
Palladium |
Platinum and palladium pieces are usually heavier than silver and more expensive.
5. Not Just Numbers: Letters and Abbreviations
Alongside numbers, you’ll often see letter codes that indicate whether your piece is solid, plated, or filled.
5.1 Solid vs Plated vs Filled
Gold Plated / Gold Filled Codes
|
Stamp |
Meaning |
|
GP |
Gold Plated (a thin gold layer) |
|
HGP |
Heavy Gold Plated |
|
GEP |
Gold Electroplated |
|
RGP |
Rolled Gold Plate |
|
GF |
Gold Filled (thicker gold layer than plated) |
|
1/20 14K GF |
1/20th of the weight is 14K gold |
Key idea:
- Solid gold: 10K, 14K, 18K, 585, 750, etc.
- Gold-filled: better and longer-lasting than gold-plated.
- Gold-plated: a very thin gold coating over a base metal.
Example:
A chain marked 1/20 14K GF is not solid 14K gold; it’s gold-filled, with 1/20 of its total weight being 14K gold bonded to a base metal core.
5.2 Stones and Materials
These stamps tell you about stones or imitations:
|
Stamp |
Meaning |
|
CZ |
Cubic zirconia (diamond simulant) |
|
LAB or LG |
Lab-grown stone |
|
GLASS |
Glass stone |
|
CR or CRYSTAL |
Crystal |
6. Maker’s Marks, Logos, and Brand Stamps
Besides metal and purity, many pieces have maker’s marks.
These might look like:
- A few letters (e.g., T&CO, PD, JW)
- A tiny logo or symbol
- Full brand names (e.g., TIFFANY & CO, SWAROVSKI)
Example Layout on a Ring
Inside of band:
14K PD ♦
14K = gold purity
PD = maker's initials
♦ = brand symbol or hallmark
Maker’s marks:
- Identify the manufacturer or designer
- Can sometimes help determine value and authenticity
- Often require referencing online databases or brand guides to decode
7. Country Hallmarks & Date Letters (Especially in Europe/UK)
In some countries (especially UK and parts of Europe), jewellery can carry a series of hallmarks rather than just simple numbers.
A full hallmark line might contain:
- Maker’s mark (e.g., AB in a rectangle)
- Metal fineness mark (e.g., 925, 750)
- Assay office mark (symbol for city that tested it – like a leopard’s head for London)
- Date letter (a letter in a particular font and shape that corresponds to a specific year)
Simplified Hallmark “Picture”
AB 925 Leopards Head y
Maker Silver London assay Year code
mark purity office (date letter)
To decode these fully, you usually need a hallmark chart or online reference (search for “UK hallmark date letters” or “[country] jewellery hallmarks”).
8. Costume Jewellery and Non-Precious Metals
Not all jewellery is made of precious metal and the stamps will reflect that.
Common Non-Precious or Base Metal Stamps
|
Stamp |
Meaning |
|
STAINLESS or STAINLESS STEEL |
Steel |
|
316L |
Surgical-grade stainless steel |
|
TI |
Titanium |
|
BRASS |
Brass |
|
NICKEL FREE |
Does not contain nickel |
|
ALLERGY FREE |
Marketing term, not standardized |
Some fashion/costume jewellery might have:
- Only a brand name and no metal purity stamp
- Or a metal stamp that refers to base metal plating (e.g., SILVERTONE is just colour, not silver content)
9. How to Read a Real-Life Example
Let’s say you look inside a ring and see:
14K FG 585
Breakdown:
- 14K → 14 karat gold
- 585 → Confirms 58.5% gold (same as 14K, standard international fineness)
- FG → Likely the maker’s or brand’s initials
Another example on a bracelet tag:
925 ITALY AG
- 925 → Sterling silver
- ITALY → Made in Italy
- AG → Chemical symbol for silver, or maker’s initials (context matters)
Another example on a chain:
GP 18K
- 18K → 18 karat gold (in plating)
- GP → Gold plated
- Meaning: Not solid 18K gold, but base metal plated with 18K gold.
10. When the Numbers Don’t Look Familiar
Sometimes you’ll see strange combinations, like:
- 375, 585, 750 (gold fineness)
- 835, 900, 935 (silver fineness in some European pieces)
- Tiny symbols without letters or numbers
If you see a number, you don’t recognize:
- Check if it’s close to a known fineness (e.g., 375 = 9K gold, common in UK).
- Look for context: Are there other stamps nearby?
- Compare shape/style: Hallmarks often use specific shapes (ovals, rectangles, shields).
11. What Does My Stamp Mean?
Use this flow-style checklist:
- Does it have K, KT, or a 3-digit number like 585, 750, 417?
- Yes → Probably gold-related
- No → Go to step 2
- Does it say 925, STER, or STERLING?
- Yes → Sterling silver
- No → Go to step 3
- Does it say PLAT, PT, or 950/900 and feel heavy?
- Yes → Likely platinum
- No → Go to step 4
- Does it include GP, GF, GEP, RGP?
- Yes → Plated or filled (not solid gold)
- No → Go to step 5
- Only letters/initials or a logo?
- Likely maker’s mark or brand mark
- No marks at all?
- Could be handmade, very old, or not precious metal; consider testing or a jeweller’s opinion.
. 
12. Should You Trust Stamps Completely?
Stamps are helpful but not infallible:
- Some old or foreign pieces may use non-standard marks
- Fake jewellery can have fake stamps
- Wear and resizing can distort or remove marks
If you’re unsure and the piece might be valuable:
- Visit a reputable jeweller or appraiser
- Ask for metal testing (acid test, XRF, etc.)
- Keep any original receipts or certificates
13. Quick Reference Summary
Gold:
- 10K / 417 → 41.7%
- 14K / 585 → 58.5%
- 18K / 750 → 75%
- 24K / 999 → 99.9%
Silver:
- 925, STER, STERLING → sterling silver
- 800 → 80% silver
- 999 → fine silver
Platinum:
- PLAT, PT, 950, 900 → platinum (usually high purity)
Plated/Filled:
- GP, HGP, GEP → gold plated
- GF, RGP, 1/20 14K GF → gold filled/rolled gold
- CZ → cubic zirconia stone