Gold Karat & Purity Guide — 18K vs 22K vs 24K Explained
When buying gold — whether jewelry, coins, or bars — the karat (K) rating tells you how pure the gold is. Higher karat means more gold content and higher value per gram.
What is a Karat?
A karat is a measure of gold purity based on a scale of 24 parts. 24 karat (24K) gold is pure gold — 24 out of 24 parts are gold. Lower karat numbers mean the gold is alloyed (mixed) with other metals like silver, copper, or zinc.
The karat system has been used since medieval times and remains the global standard for expressing gold purity.
Karat Purity Chart
| Karat | Purity % | Fineness | Gold per Gram | Common Use |
|---|---|---|---|---|
| 24K | 99.9% | 999 | 0.999g | Investment bars, SJC gold |
| 22K | 91.67% | 916 | 0.9167g | Indian jewelry, coins |
| 21K | 87.5% | 875 | 0.875g | Middle East jewelry |
| 18K | 75.0% | 750 | 0.750g | Fine jewelry worldwide |
| 14K | 58.33% | 583 | 0.5833g | US/European everyday jewelry |
| 10K | 41.67% | 417 | 0.4167g | Budget jewelry (US minimum) |
| 9K | 37.5% | 375 | 0.375g | UK/Australia minimum |
How to Calculate Gold Value by Karat
The formula is straightforward:
Gold Value = Spot Price × (Karat ÷ 24) × Weight
For example, with gold at $4,500/oz and a 10-gram 18K necklace:
- Gold content: 10g × (18 ÷ 24) = 7.5g of pure gold
- Price per gram: $4,500 ÷ 31.1035 = $144.68/g
- Gold value: 7.5g × $144.68 = $1,085.10
Note: This calculates the melt value (raw gold content). Jewelry retail prices include craftsmanship, brand premium, and dealer margins.
Calculate Gold Value by Karat
Enter your gold weight to see values across different purities based on the current spot price.
| Karat | Purity | Price/Gram | Total Value |
|---|---|---|---|
| 24K | 99.9% | $132.61 | $1,326.11 |
| 22K | 91.7% | $121.73 | $1,217.26 |
| 21K | 87.5% | $116.15 | $1,161.51 |
| 18K | 75.0% | $99.56 | $995.58 |
| 14K | 58.3% | $77.39 | $773.90 |
| 10K | 41.7% | $55.35 | $553.54 |
Based on current gold spot price: $4,128.80/oz. For more tools, visit our Gold Calculator.
Fineness vs. Karat
While karat is the traditional system, fineness (parts per thousand) is used in bullion markets and hallmarking.
| Fineness | Karat | Description |
|---|---|---|
| 999.9 | 24K | Four-nines fine (investment grade) |
| 999 | 24K | Three-nines fine |
| 995 | 24K | LBMA Good Delivery minimum |
| 916 | 22K | Common in Indian/Middle Eastern gold |
| 750 | 18K | Standard fine jewelry |
| 585 | 14K | Common in Western markets |
Regional Purity Standards
Vietnam
24KSJC 999.9
Vietnam's national gold standard is SJC (Saigon Jewelry Company) gold bars, refined to 999.9 fineness. SJC bars trade at a premium over international spot prices due to limited supply and government regulation.
India
22K916
India, the world's second-largest gold consumer, traditionally favors 22K (916) gold for jewelry. The hallmarking system (BIS) certifies purity. Investment-grade bars are 999 fineness.
China
24KAu999 / Au9999
The Shanghai Gold Exchange trades gold at 999 and 9999 fineness. Chinese gold jewelry uses 999 (千足金) or 9999 (万足金) standards.
United States
14K14K Standard
14K is the most popular karat for jewelry due to its balance of durability and gold content. By law, anything sold as "gold" must be at least 10K.
Thailand
~23K96.5%
Thailand uses a unique standard of 96.5% purity (approximately 23.16 karat), specific to Thai gold trading. This is neither 22K nor 24K.
Middle East
21-22K21K / 22K
Gulf states (UAE, Saudi Arabia, Kuwait) favor 21K and 22K gold jewelry. Dubai's Gold Souk is one of the world's largest retail gold markets.
How Karat Affects Durability
Pure 24K gold is soft and malleable — not ideal for rings or bracelets that endure daily wear. Lower karat gold is harder and more durable because of the alloyed metals:
Very soft, bends easily. Best for bars and protected jewelry.
Slightly harder, popular for traditional jewelry.
Good balance of purity and durability. The standard for fine jewelry.
Very durable. Ideal for engagement rings and everyday pieces.
Hardest, most scratch-resistant. Most affordable gold option.
Color Variations by Alloy
The metals mixed with gold change its color:
Yellow Gold
Gold + silver + copper (classic gold color)
White Gold
Gold + palladium or nickel (often rhodium-plated)
Rose Gold
Gold + copper (pinkish hue, trendy in modern jewelry)
The karat rating is the same regardless of color — 18K white gold has the same 75% gold content as 18K yellow gold.
Testing Gold Purity
Common methods to verify gold karat:
Hallmark stamps
Look for "750" (18K), "916" (22K), or "999" (24K) stamped on the piece
Acid test
A drop of acid on a scratch mark reveals purity by reaction color
Electronic tester
Non-destructive device that measures conductivity
XRF analyzer
Professional-grade X-ray fluorescence analysis (most accurate)
Understanding gold karat helps you make informed purchases and accurately value your gold holdings. Use our Gold Calculator to instantly convert prices across different karats and weight units, or check the live gold price for current spot rates.