Gold is one of the most cherished metals in India, symbolizing wealth, security, and tradition. But not all gold is created equal. When you buy or sell gold, you'll often hear terms like 24K, 22K, 18K, or 14K gold. These numbers refer to karats, a measure of gold purity.

To make informed decisions-whether you're buying jewellery or selling old gold-it's important to understand what karat means, how purity is calculated, and what it implies in terms of value. Let's break it down with clear explanations and examples.

What Does Karat Mean?

The word karat (K) is a unit that denotes the proportion of pure gold in a given piece. Pure gold is 24 karats (24K). Since gold in its pure form is soft and malleable, jewellers often mix it with other metals like copper, silver, or zinc to make it more durable.

• 24K gold = 99.9% pure gold
• 22K gold = 91.6% pure gold
• 18K gold = 75% pure gold
• 14K gold = 58.3% pure gold

The remaining percentage is made up of other metals that provide strength and shape.

The Math Behind Gold Purity

The formula for calculating gold purity is:

Purity (%) = (Karat / 24) × 100

This formula converts karats into percentage purity. Let's see how it works.

Example 1: 22K Gold

Purity = (22 ÷ 24) × 100 = 91.6%

This is why 22K gold is also referred to as 916 gold in India.

Example 2: 18K Gold

Purity = (18 ÷ 24) × 100 = 75%

So, in 18K gold jewellery, 75% is pure gold and 25% is alloy metals.

Example 3: 14K Gold

Purity = (14 ÷ 24) × 100 = 58.3%

This type of gold is common in lightweight or studded jewellery.

Practical Weight and Purity Calculation

When buying or selling gold, the actual value is based on the weight of pure gold content.

Example 1: Selling 10 grams of 22K gold

• Gold purity = 91.6%
• Pure gold weight = 10 × 0.916 = 9.16 grams

So, even though your jewellery weighs 10 grams, its pure gold content is only 9.16 grams.

Example 2: Buying 8 grams of 18K gold

• Gold purity = 75%
• Pure gold weight = 8 × 0.75 = 6 grams

The remaining 2 grams are alloy metals.

Different Karats and Their Uses

24K Gold (99.9% pure)

• Too soft for jewellery
• Used in gold coins, bars, and sometimes in medical/electronic equipment

22K Gold (91.6% pure)

• Most common in Indian jewellery
• Strong enough for designs, while still retaining high purity

18K Gold (75% pure)

• Popular for diamond and gemstone-studded jewellery, as it provides durability
• Also used in watches and modern designs

14K Gold (58.3% pure)

• Common in lightweight jewellery
• Cheaper but less valuable when reselling

Hallmarking and Karat Verification

In India, BIS (Bureau of Indian Standards) hallmarking certifies the purity of gold. Hallmarked jewellery typically has:

• BIS logo
• Karat and fineness number (e.g., 22K916)
• Jeweller's identification mark

💡 Tip: Always insist on hallmark jewellery. It ensures transparency in purity and helps you fetch better resale value.

Why Purity Matters in Gold Transactions

Resale Value

Higher purity gold (22K/24K) usually fetches better value when selling. Lower karat jewellery may result in deductions.

Durability vs Value

While 24K is purest, 22K and 18K are more practical for daily wear jewellery.

Investment vs Usage

• For investment → prefer 24K coins/bars
• For jewellery → prefer 22K or 18K for balance of purity and strength

Real-Life Example of Resale Calculation

Suppose you're selling 15 grams of 22K gold jewellery, with the gold rate at ₹6,000 per gram (24K).

Step 1: Convert to 24K equivalent weight

Pure gold = 15 × 0.916 = 13.74 grams

Step 2: Multiply by 24K rate

13.74 × 6,000 = ₹82,440 (before deductions)

This is the approximate value you should expect, though jewellers may deduct making charges or wastage.

Conclusion

Understanding gold purity in karats is crucial before buying or selling gold in India. The math is simple-divide the karat by 24 to find percentage purity. Remember that jewellery always contains some alloy, and its resale value depends on the pure gold content.

• 24K = best for investment
• 22K = ideal for traditional jewellery
• 18K/14K = suitable for durable, studded designs

By knowing how karats translate into purity and value, you'll be better equipped to make smart gold transactions and ensure you get the right price for your precious metal.