Understanding Gold Purity — Karats Explained

A karat (abbreviated as “K” or “kt”) is the unit used to measure the purity of gold. The karat system divides gold into 24 parts. Pure gold is 24 karats — meaning all 24 parts out of 24 are gold with no other metals mixed in.

When gold is less than 24K, it means some of those 24 parts are replaced by other metals (called alloy metals) such as copper, silver, zinc, or nickel. These metals are added to improve durability, change colour, or reduce cost.

Note:“Karat” (gold purity) should not be confused with “carat” (the unit used to measure the weight of gemstones). In Sri Lanka, “karat” is sometimes spelled “carat” when referring to gold — both refer to the same purity measurement.

24K gold is the purest form commercially available, containing 99.9% gold. Its rich, deep yellow colour is unmistakable. However, pure gold is inherently soft — it can be scratched with a fingernail and will bend under pressure. This is why 24K gold is primarily used for investment purposes in the form of bars, coins, and biscuits rather than wearable jewelry.

In Sri Lanka, 24K gold bars are available at major jewellers and banks. If you are buying 24K gold as an investment, ensure it comes with a 999 hallmark, a certificate of authenticity, and a serial number. Check today's 24K gold price in Sri Lanka.

21K gold sits between the high purity of 22K and the enhanced durability of 18K. With 87.5% gold content, it is a practical choice for intricate jewelry designs such as filigree work, where the metal needs to be strong enough to hold delicate patterns without breaking. The 875 hallmark identifies 21K gold.

In Sri Lanka, 21K gold is particularly popular in the Northern and Eastern provinces, where it is commonly used for traditional Tamil jewelry designs. It is also a practical budget alternative to 22K — offering gold that still looks and feels like high-purity gold at a lower per-gram cost. Many buyers choose 21K when they want larger or heavier pieces without the full 22K price tag.

Check today's 21K gold price in Sri Lanka to see current rates per gram and per pawn.

18K gold is the most durable of the commonly available gold purities, containing 75% gold and 25% alloy metals. The higher alloy content makes it significantly harder and more scratch-resistant than 22K or 24K gold, which is why it is preferred for items that endure daily wear, such as engagement rings and watches.

The key advantage of 18K gold is its versatility in colour options. While 22K and 24K gold are only available in yellow, 18K gold can be alloyed to create white gold (a popular alternative to platinum) and rose gold (an increasingly trendy option for modern designs). These colour variations are achieved by adjusting the alloy metals mixed with the gold.

In Sri Lanka, 18K gold is becoming more popular among younger buyers who prefer contemporary, western-style jewelry designs. Major brands like Vogue Jewellers and Mallika Hemachandra offer extensive 18K collections. Check today's 18K gold price in Sri Lanka.

Verifying gold purity is essential to ensure you are getting what you pay for. Here are the most reliable methods available in Sri Lanka:

Hallmarks are small stamps engraved on gold jewelry that indicate purity. Here is what to look for when buying gold in Sri Lanka:

What to Look For on the Stamp

• • Purity number (916, 875, 750, or 999) — this is the most important marking
• • Manufacturer's mark — initials or logo of the jeweller who made the piece
• • Assay office mark — indicates which testing authority verified the purity
• • Year mark — some stamps include the year of manufacture