24K vs 22K vs 18K vs 14K: What Gold Purity Really Means

When you purchase gold jewelry, you are entrusting a number that is on a clasp. The stamp will indicate that amount of gold in the item and much of the value of that item. However, many buyers are not aware of what the number represents, which grades are appropriate for which uses and how the hallmarking system ensures their protection.

This article will explain the common types of gold and their pros and cons, how it gets hallmarked in India, the United Kingdom and the United States, and how to check the gold you're purchasing.

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The meaning of the karat number

In the 24-point purity rating, a higher number indicates a higher degree of purity. 24K or 24 karats means that the gold is pure. The numbers in the 'K' refer to the ratio of how much gold to other metals used in the alloy, so 22K is 22 parts gold to 2 parts other metals. The same grades are expressed in fineness, as parts per thousand:

• 24K: 999 fineness, about 99.9 percent gold
• 22K: 916 fineness, about 91.7 percent gold
• 18K: 750 fineness, 75 percent gold
• 14K: 585 fineness, about 58.5 percent gold
• 10K: 417 fineness, about 41.7 percent gold
• 9K: 375 fineness, 37.5 percent gold

The non-gold part is an alloy. Colour and hardness depend on the metals used. Yellow gold results from copper and silver, rose gold from copper in higher quantities, and white gold from white metals like palladium or nickel, rhodium-plated for a shiny finish.

Comparing the common grades

24K (999)

The purest and richest in color, 24K is very soft and bends or scratches easily. It is used for rings and bracelets in certain cultures, but it's not an ideal choice for everyday jewelry - more suited to bullion bars and coins.

22K (916)

A traditional standard in India, the Middle East and Southeast Asia. It retains the deep yellow hue of high purity gold and is just firm enough for bangles, necklaces and wedding jewelry. More complex or fixed pieces are more likely to wear over time.

18K (750)

A popular blend of purity and durability found in European and international fine jewelry. It maintains high gold content while being scratch resistant and keeping stones in place.

14K (585)

The most frequently used grade in the United States. It is hard, affordable, and suited to daily-wear rings and chains. Lower gold content corresponds to less intrinsic metal value per gram.

10K and 9K

Lower grades common in budget jewelry. 9K is extensively sold in the United Kingdom. The minimum standard for legally calling a product 'gold' in the U.S. is 10K. High alloy content makes these grades durable but can cause tarnish and skin irritation.

What is hallmarking and why it matters

A hallmark is an official stamp, typically by an independent testing lab, that guarantees the purity of a precious metals piece. It is different from the manufacturer's own stamp. Hallmarking gives buyers the protection of third-party verification rather than a seller's claim.

Hallmarking in India

The Bureau of Indian Standards (BIS) runs the national hallmarking scheme. Gold jewellery hallmarking was made compulsory in a phased manner, and a six-character alphanumeric code called HUID (Hallmark Unique Identification) was developed. A BIS hallmark includes: the BIS logo, the purity grade (such as 22K916, 18K750 or 14K585), and the HUID code. Buyers can verify the HUID using the BIS Care App or website.

Hallmarking in the United Kingdom

The UK's hallmarks are among the oldest in the world, regulated by the Hallmarking Act 1973, and carried out by independent assay offices in London, Birmingham, Sheffield and Edinburgh. For gold items over 1 gram, hallmarking is a legal requirement. A UK hallmark traditionally includes: a sponsor's mark showing who made or imported the item, a fineness mark (e.g. 375 or 750), and an assay office mark.

Karat marking in the United States

There is no national marking scheme in the USA. Instead, the FTC Jewelry Guides and the National Gold and Silver Stamping Act govern marking. Where a karat mark appears, it must be followed by the maker's registered trademark. Terms like 'gold filled', 'gold plated' and 'gold vermeil' each have specific legal meanings. Since there is no independent hallmark in the U.S., it is especially important to purchase from reputable sellers.

How to test if jewelry is real

• Look for marks. Check for a purity mark and/or hallmark (use a magnifying loupe if necessary). Note that a stamp alone is not proof.
• Ask for documentation. A reputable jeweller should issue an invoice showing weight, purity and applicable hallmarks.
• Use a professional test. X-ray fluorescence (XRF) analyzers are accurate and non-destructive. Acid tests and electronic testers are less accurate alternatives.
• Do simple checks. Real gold does not discolor skin and is not magnetic, but these are subtle signs and cannot prove purity.
• Verify weight. Weigh using a calibrated scale, preferably in front of the seller.

Disclaimer: The information contained in this article is provided for general education purposes only and should not be construed as financial, investment, tax or legal advice. Hallmarking rules differ by country and may change; consult current regulations in your jurisdiction.