Understanding Gold Purity: 24K, 22K, 18K Explained
When you walk into a jewellery shop, you'll encounter terms like 24K, 22K, 916, 750, and BIS hallmark. This guide explains what all of these mean and how to choose the right gold purity for your purpose.
What is a Karat?
A karat (K) is a unit that measures the proportion of pure gold in an alloy. Pure gold is 24 karats — meaning all 24 parts are gold. Lower karats mean more alloy metals (like copper, silver, or zinc) are mixed in.
The formula is simple: Purity % = (Karat ÷ 24) × 100
So 22K gold = (22 ÷ 24) × 100 = 91.67% pure gold. This is why 22K jewellery carries the 916 hallmark (91.6%).
All Gold Purity Levels Compared
| Karat | Purity | BIS Mark | Color | Common Use |
|---|---|---|---|---|
| 24K | 99.9% | 999 | Bright Yellow | Coins, bars, investment |
| 23K | 95.8% | 958 | Deep Yellow | Rare, limited use |
| 22K (Most popular) | 91.6% | 916 | Rich Yellow | Jewellery (most popular in India) |
| 21K | 87.5% | 875 | Yellow | Gulf region jewellery |
| 18K | 75.0% | 750 | Lighter Yellow | Diamond jewellery, luxury watches |
| 14K | 58.3% | 585 | Pale Yellow | Fashion jewellery, Western markets |
| 10K | 41.7% | 417 | Very Pale | Entry-level jewellery |
| 9K | 37.5% | 375 | Pale | UK market jewellery |
24K Gold — Pure Gold
24K gold is 99.9% pure gold with virtually no other metals. It has the richest, brightest yellow color of all gold purities. However, pure gold is extremely soft and malleable — it bends, scratches, and deforms easily with daily wear.
Best For
- ✓ Gold coins and bars
- ✓ Investment purchases
- ✓ Electronic components
- ✓ Medical/dental uses
Not Suitable For
- ✗ Daily-wear jewellery
- ✗ Rings or bangles
- ✗ Intricate designs
- ✗ Stone settings
24K gold commands the highest price per gram — all other karats are priced as a proportion of 24K. On GoldRate.app, the 24K rate is the base price used to derive 22K and 18K prices.
22K Gold (916) — India's Most Popular Jewellery Gold
22K gold contains 91.6% pure gold and 8.4% alloys (usually copper, silver, or zinc). The alloys give it the strength needed for intricate jewellery designs while maintaining a rich yellow color.
Why 22K Dominates Indian Jewellery
- • Cultural preference — Indian buyers associate brighter yellow gold with high purity and value
- • Durable enough for intricate designs like temple jewellery, jhumkas, and traditional bangles
- • High resale value — widely accepted by jewellers across India for exchange
- • BIS 916 certification makes it easy to verify and trust
The price of 22K gold per gram = 24K price × 0.916. For example, if 24K gold is ₹8,000/g, then 22K = ₹8,000 × 0.916 = ₹7,328/g.
18K Gold (750) — For Diamond Jewellery
18K gold contains 75% pure gold and 25% alloy metals. The higher alloy content makes it harder and more durable, making it ideal for prong settings that hold diamonds and other precious stones.
18K gold is available in multiple colors depending on the alloy mix:
Yellow Gold
Traditional copper/silver alloy
White Gold
Palladium or nickel alloy + rhodium plating
Rose Gold
Higher copper content gives pink hue
In India, 18K gold is preferred for diamond-studded jewellery, luxury watches, and contemporary designs. It costs roughly 75% of 24K gold price.
Gold Colors: Yellow vs White vs Rose
Yellow Gold
The classic, traditional gold color. Achieved with copper and silver alloys. The most popular in India and highly resaleable. 22K yellow gold dominates the Indian jewellery market.
White Gold
Made by alloying gold with white metals (palladium, silver, or nickel) and then rhodium plating for a bright silvery finish. Popular for engagement rings in Western markets. Requires re-plating every few years as rhodium wears off.
Rose Gold (Pink Gold)
Made by increasing the copper content in the alloy. The copper gives a warm pinkish-red hue. Growing in popularity for modern jewellery designs in India. 18K rose gold is the most common variant.
How to Calculate Gold Value by Purity
If you know the 24K (pure gold) price, you can calculate any karat price:
Use our Gold Calculator to compute the exact value of your gold based on weight, karat, and current market price.
FAQs — Gold Purity
What does 916 mean on gold jewellery?
916 is the BIS hallmark for 22K gold, indicating 91.6% purity. It means 916 parts out of 1000 are pure gold and the remaining 84 parts are alloy metals.
Is 22K or 24K gold better for investment?
For investment, 24K gold (coins, bars, Sovereign Gold Bonds, or Gold ETFs) is better because you pay for gold value without making charges. 22K jewellery has making charges that reduce your return when reselling.
Can 22K gold turn black or tarnish?
High-quality 22K BIS hallmarked gold should not tarnish. Blackening can occur if the gold is of lower purity than stated (i.e., adulterated) or if it comes in contact with harsh chemicals.
What is the difference between 18K and 22K gold in terms of price?
18K gold costs approximately 82% of 22K gold price (since 18K = 75% pure, 22K = 91.6% pure, ratio = 75/91.6 ≈ 0.819). For example, if 22K is ₹7,200/g, then 18K ≈ ₹5,900/g.
How do I test if my gold is real?
Methods include: (1) Acid test by a certified jeweller, (2) XRF (X-ray fluorescence) machine test available at BIS-certified testing centres, (3) Magnet test — real gold is not magnetic. Always prefer BIS hallmarked gold to avoid the need for testing.
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