---
title: "Gold Purity and Hallmarks Explained"
source: "https://goldealers.co.uk/knowledge/gold/gold-purity-hallmarks"
date: "2025-12-02"
---

# Gold Purity and Hallmarks Explained

Understanding gold purity is key to knowing your gold's value. In this educational guide, we explain carat ratings (9ct, 14ct, 18ct, 22ct, 24ct) and the UK hallmark system. At Goldealers, we examine hallmarks on items to quickly gauge purity, ensuring accurate valuations.

> **Quick Summary:** Gold purity is measured in carats (ct), with 24ct being pure gold. UK hallmarks show fineness numbers like 375 (9ct) or 750 (18ct) that indicate the percentage of gold content. Understanding these markings helps you estimate your item's value before selling.

## What Carats Mean

Carat (ct or K) is the measure of gold fineness out of 24 parts. Pure gold is 24ct, meaning 24 out of 24 parts are gold.

### Carat to Percentage Conversion

| Carat | Fineness | Percentage | Pure Gold in 10g Item |
|-------|----------|------------|----------------------|
| 9ct | 375 | 37.5% | 3.75g |
| 14ct | 585 | 58.5% | 5.85g |
| 18ct | 750 | 75% | 7.5g |
| 22ct | 916 | 91.6% | 9.16g |
| 24ct | 999 | 99.9% | 9.99g |

> The higher the carat number, the more pure gold the item contains and thus the higher its scrap value per weight. Even lower-purity gold has proportional value.

### Common UK Purities

**9ct (375)** - Most common in UK jewellery
- 37.5% pure gold
- More durable and scratch-resistant
- Lower price point when new
- Still valuable as scrap

**18ct (750)** - Premium jewellery standard
- 75% pure gold
- Richer gold colour
- Good balance of purity and durability
- Higher scrap value per gram

**22ct (916)** - Traditional and investment gold
- 91.6% pure gold
- Used in Asian jewellery and some coins
- Very high gold content
- Near-pure scrap value

**24ct (999)** - Pure gold
- 99.9% pure gold
- Too soft for most jewellery
- Used in bullion bars and investment
- Maximum scrap value

## UK Hallmarking Basics

The UK has one of the world's oldest and most trusted hallmarking systems, dating back over 700 years.

### Legal Requirements

**Mandatory Hallmarking:**
- All gold items over 1 gram must be hallmarked
- Must be tested by an official Assay Office
- Applies to items sold in the UK
- Penalties for selling unmarked gold items

**Exempt Items:**
- Items under 1 gram weight
- Antiques made before 1950 (but may still have hallmarks)
- Items not sold as gold

[Can I sell gold that isn't hallmarked?](/knowledge/gold/can-sell-gold-not-hallmarked)

### Hallmark Components

A complete UK hallmark contains up to four marks:

**1. Sponsor's (Maker's) Mark**
- Identifies who made or submitted the item
- Usually initials in a shield shape
- Example: "JW" for a jeweller named John Wilson

**2. Fineness Mark**
- Shows the gold purity
- Common marks: 375, 585, 750, 916, 999
- Sometimes shown with crown symbol

**3. Assay Office Mark**
- Indicates which office tested the item
- London: Leopard's head
- Birmingham: Anchor
- Sheffield: Rose/Crown
- Edinburgh: Castle

**4. Date Letter (optional on newer items)**
- Indicates year of hallmarking
- Cycles through alphabet
- More common on antique pieces

> Goldealers' experts are trained in reading all UK hallmarks. We can identify the purity, age, and origin of your items from these tiny marks.

## Reading Hallmarks

### Where to Find Hallmarks

**Rings:**
- Inside the band
- Sometimes very tiny requiring magnification

**Necklaces & Bracelets:**
- On or near the clasp
- Sometimes on a separate tag

**Earrings:**
- Behind the setting
- On the post or clasp

**Bangles:**
- Inside edge
- Near the opening

### Common Hallmark Examples

**Modern 9ct Ring:**
```
[JW] [375] [⚓] = Made by JW, 9ct gold, tested in Birmingham
```

**18ct Necklace:**
```
[AB] [750] [🦁] = Made by AB, 18ct gold, tested in London
```

**22ct Asian Jewellery:**
```
[916] [RS] = 22ct gold, maker RS
```

> Use a magnifying glass or smartphone macro lens to clearly see hallmarks. Good lighting is essential as these marks are often very small.

## Why Purity Matters for Value

The purity directly determines the amount of pure gold in your item, which is the basis for scrap valuation.

### Value Example

Consider two rings, both weighing 5 grams:

**9ct Ring:**
- Pure gold: 5g × 37.5% = 1.875g
- Value at £50/g: £93.75

**18ct Ring:**
- Pure gold: 5g × 75% = 3.75g
- Value at £50/g: £187.50

The 18ct ring has exactly double the gold content and thus double the scrap value, despite the same total weight.

[Complete guide to scrap gold valuation](/knowledge/gold/what-is-scrap-gold-valued)

## International Hallmarks

Different countries use different marking systems, but the concept of purity remains the same.

### Common Foreign Marks

**US System:**
- Uses "K" instead of "ct"
- "14K" = 14 carat
- May not show fineness number

**European System:**
- Often shows fineness only
- "585" without "14ct" designation
- May have different assay marks

**Asian Jewellery:**
- Often marked in local language
- May show percentage (e.g., "91.6%")
- Sometimes no hallmark at all

> Foreign jewellery may not follow UK hallmarking standards. Goldealers tests all items regardless of markings to verify actual gold content.

## Testing Purity Without Hallmarks

If hallmarks are absent, worn off, or unclear, dealers use professional testing methods to determine purity.

### Professional Testing Methods

**XRF Analysis (Goldealers' primary method):**
- Non-destructive
- Instant results
- Highly accurate
- Tests actual composition

**Acid Testing:**
- Traditional method
- Requires small scratch
- Confirms minimum purity
- Used as verification

[How dealers test gold for authenticity](/knowledge/testing/how-is-gold-tested)

## Fake or Misleading Hallmarks

Unfortunately, some items carry fake hallmarks or markings that don't reflect their true composition.

### Warning Signs

**Suspect Markings:**
- "GP" or "GF" = Gold Plated or Gold Filled (not solid gold)
- "HGE" = Heavy Gold Electroplate
- No assay office mark on UK items over 1g
- Unusual fineness numbers (e.g., "400" or "800" for gold)
- Hallmarks that rub off easily

> Some costume jewellery may be stamped "18K" but is actually just gold-plated. Professional testing catches these fakes. Goldealers always verifies the metal content regardless of stamps.

### How Goldealers Protects You

We never rely solely on hallmarks:
1. Visual inspection of markings
2. XRF testing for actual composition
3. Acid test verification if needed
4. Weight and density checks
5. Transparent communication of results

If stamps don't match the actual gold content, we'll explain this clearly and pay based on the verified purity.

## Frequently Asked Questions

**Q: How can I tell how pure my gold is?**  
A: Check the hallmark on your gold item. In the UK, gold above 1g usually has a hallmark number like 375 (9ct), 750 (18ct), etc., indicating its purity. The higher the number or carat (up to 24ct for pure gold), the more gold content it has. If unsure or no hallmark is present, a dealer like Goldealers can test the item to determine its purity.

**Q: Is 9ct gold worth selling?**  
A: Yes, absolutely. While 9ct gold has lower purity (37.5%), it still contains valuable gold. Many UK jewellery pieces are 9ct, and Goldealers pays fair market rates based on the actual gold content.

**Q: Can hallmarks be wrong or fake?**  
A: Yes, unfortunately some items have incorrect or fake hallmarks. This is why reputable dealers like Goldealers always test items professionally rather than relying solely on stamps.

**Q: Does older gold have different hallmarks?**  
A: Yes, antique gold may have older hallmarking styles, different symbols, or even no hallmark if exempt under old rules. We can still test and value these items accurately.

**Q: What if my item has a carat stamp but no hallmark?**  
A: Items from outside the UK may have carat stamps without UK hallmarks. We'll test these items to verify the actual purity and pay based on the confirmed gold content.

## Next Steps

Armed with hallmark knowledge, you can identify your gold's purity at home and verify that quotes you receive align with your item's carat grade.

**Useful Resources:**
- [Understanding UK gold hallmarks in detail](/knowledge/gold/understanding-gold-hallmarks-uk)
- [How XRF testing determines gold purity](/knowledge/testing/how-does-xrf-testing-work)
- [Selling unhallmarked gold items](/knowledge/gold/can-sell-gold-not-hallmarked)

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*Published by Goldealers Ltd · https://goldealers.co.uk/knowledge/gold/gold-purity-hallmarks*