The difference is the share of gold: 21K is 87.5% pure gold (21 ÷ 24) and 18K is 75% (18 ÷ 24), and the rest is other metals that strengthen the piece. So a gram of 18K costs about 85.7% of a gram of 21K (18 ÷ 21). Today 21K is 408.86 SAR per gram and 18K is 350.45 SAR, so a 10 g piece holds 4,088.60 SAR of gold if it is 21K and 3,504.51 SAR if it is 18K. 21K suits saving better because it holds more gold; 18K is harder and better for daily wear and fine designs.
What is the difference between 21K and 18K gold?
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What exactly does karat mean?
Karat measures the purity of gold out of 24. Pure gold is 24K, and any lower karat means other metals (such as copper or silver) are mixed in so that it becomes harder and stands up to use, because pure gold is soft.
| Karat | Gold content | Hallmark | Price per gram today |
|---|---|---|---|
| 24K | 99.9% | 999 | 467.27 SAR |
| 21K | 87.5% | 875 | 408.86 SAR |
| 18K | 75% | 750 | 350.45 SAR |
The hallmark is mandatory: Article 8 of the Precious Metals and Gemstones Law says items are hallmarked according to their karat, at one of the official karats set by the Ministry of Commerce. So the number stamped on the piece tells you its karat.
Which is better, 21K or 18K?
It depends on your goal:
- 21K: the most common karat in Saudi Arabia and the Gulf. It holds more gold, so its value when you sell is closer to the gold price. Today a shop buys used 21K at about 403.86 SAR per gram, against 345.45 SAR for 18K.
- 18K: cheaper per gram, harder and less prone to bending and scratching, and common in modern designs and pieces with stones.
If your goal is saving or a piece that holds its value, 21K is the closer fit. If your goal is a piece worn every day or a fine design, 18K is usually more suitable.
Example: the same weight in two karats
A 20 g bracelet:
| 21K | 18K | |
|---|---|---|
| Pure gold in it | 20 × 87.5% = 17.5 g | 20 × 75% = 15 g |
| Gold value today | 8,177.20 SAR | 7,009.03 SAR |
| A shop buys it used at about | 8,077.20 SAR | 6,909.03 SAR |
The difference is 2.5 g of pure gold in the same weight. On top of the gold value, a shop adds the making charge and 15% VAT, and the total varies from shop to shop. How to work it out is in How do I know if a gold shop's price is fair?
How do I find a piece's karat before buying?
From the stamped hallmark (875 for 21K, 750 for 18K) and the invoice, which must show the karat and weight. Details are in How can I check that gold is real and find its true karat?, and the value of any weight and karat is in the gold calculator.
Sources
- Bureau of Experts at the Council of Ministers: Precious Metals and Gemstones Law, Article 8, hallmarking by karat (Arabic).
- Gold content is worked out from the karat (karat ÷ 24), and today's prices come from Dhahabi's price source.
Frequently asked questions
How much gold is in 21K and 18K?
21K is 87.5% pure gold and 18K is 75%. The rest is other metals, such as copper or silver, which make the piece harder.
Which costs more, 21K or 18K?
21K costs more per gram because it holds more gold. Today 21K is 408.86 SAR per gram and 18K is 350.45 SAR, before the making charge and VAT.
Which is better for saving?
Usually 21K, because it holds more gold and its value when you sell is closer to the gold price. 18K is better suited to daily use and fine designs.
How do I find a piece's karat before buying?
From the hallmark stamped on the piece (875 for 21K, 750 for 18K) and the invoice showing the karat and weight.