Gold Purity Guide: 9K to 24K Explained

Gold is rarely found in its pure form in everyday jewellery and products. Instead, pure gold is combined with other metals to create alloys with varying purity levels, hardness, and colour. The purity of gold is expressed in karats (K), a scale from 0 to 24, where 24K represents pure gold. This guide explains every karat you are likely to encounter.

How the Karat System Works

The karat number tells you how many parts out of 24 are pure gold. For example, 18K gold contains 18 parts gold and 6 parts other metals. The formula is:

This is different from the European millesimal fineness system, which expresses purity in parts per thousand (e.g. 750 = 75.0% = 18K).

Complete Gold Karat Reference Table

Karat	Purity %	Fineness	Hallmarks	Common Uses
24K	99.99%	999	24K, 999, 24ct	Bullion bars, coins, electronics, plating
22K	91.67%	916	22K, 916, 22ct	Indian bridal jewellery, some coins
21K	87.50%	875	21K, 875	Middle Eastern jewellery
18K	75.00%	750	18K, 750, 18ct	Fine jewellery, European standard
14K	58.33%	585	14K, 585, 14ct	US everyday jewellery, engagement rings
10K	41.67%	417	10K, 417, 10ct	Budget US jewellery, minimum US legal
9K	37.50%	375	9K, 375, 9ct	UK/Australian budget jewellery, minimum EU
8K	33.33%	333	8K, 333	German budget jewellery

24K Gold — Pure Gold

24K gold is as pure as gold gets for commercial purposes — 99.99% pure. It has a distinctively bright, deep yellow colour that lower-karat alloys cannot match. However, 24K gold is very soft and scratches easily, making it impractical for most jewellery. It is primarily used for bullion bars and coins, gold plating, and specialist electronics where electrical conductivity is critical.

22K Gold

At 91.67% purity, 22K gold is very close to pure gold in appearance and value, while being slightly harder. It is the standard for Indian and South Asian bridal jewellery, where high gold content is culturally valued. Some sovereign gold coins, such as the South African Krugerrand, are struck in 22K gold.

18K Gold — The Fine Jewellery Standard

18K gold (75% pure) is considered the premium standard for fine jewellery worldwide, particularly in Europe. It strikes an excellent balance between high gold content, rich colour, and sufficient hardness for detailed craftsmanship. Most luxury jewellery brands use 18K gold. The European hallmark is 750.

14K Gold — The US Everyday Standard

14K gold (58.33% pure) is the most popular gold alloy for jewellery in the United States. Its higher alloy content makes it more durable and more affordable than 18K, while still carrying substantial gold value. It is the most common choice for engagement rings and wedding bands in the US market. Marked as 585 in Europe.

10K Gold — US Minimum Legal Standard

10K gold (41.67% pure) is the minimum purity that can legally be sold as “gold” in the United States under Federal Trade Commission guidelines. It is the most affordable gold alloy, highly durable, but noticeably less rich in colour than higher karats. Common in budget fashion jewellery. Marked as 417.

9K Gold — UK and EU Minimum

9K gold (37.5% pure) is the minimum legal standard in the United Kingdom and is widely used in affordable British jewellery. It contains more alloy than gold, giving it a paler yellow colour. It is, however, extremely durable and affordable. Marked as 375.

Which Karat Is Right for You?

• Investment / maximum value: 24K bullion bars or coins
• Fine jewellery / European standard: 18K
• Everyday US jewellery / durability: 14K
• Budget jewellery / maximum hardness: 10K (US) or 9K (UK)