18K vs 22K vs 24K Gold: Purity, Price & Best Use

Understanding Gold Purity: Karats vs. Fineness

In India, gold purity is commonly discussed in Karats (K), but jewelers also use the Fineness scale. Karat measures purity on a scale of 24 parts, while Fineness measures parts per 1,000. For instance, "916 gold" is simply 22K gold (91.6% pure).

24K vs 22K vs 18K: Which Should You Buy?

Choosing the right purity depends on whether you are looking for an investment or a wearable ornament.

• 24K Gold (99.9% Pure): This is the purest form of gold. Because it is extremely soft and malleable, it cannot be used for intricate jewelry as it would bend or lose shape easily. It is ideal for investment in the form of gold biscuits, bars, or coins.
• 22K Gold (91.6% Pure): Often referred to as "916 Hallmark Gold," this is the gold standard for traditional Indian jewelry. It contains 8.4% alloys (like copper or silver) to make the jewelry durable enough for wedding sets and heavy necklaces.
• 18K Gold (75% Pure): If you are buying diamond or gemstone-studded jewelry, 18K is the best choice. The 25% alloy content makes the gold much harder, providing the strength needed to hold precious stones securely in place.

How to Check Gold Purity: The BIS Hallmark Guide

To protect consumers, the Bureau of Indian Standards (BIS) mandates hallmarking. Since April 2023, every piece of hallmarked jewelry must have a 6-digit HUID (Hallmark Unique Identification) code.

What to look for on your jewelry:

• BIS Logo: The triangular mark.
• Purity Mark: e.g., 22K916 or 18K750.
• HUID Number: A unique alphanumeric code you can verify on the BIS Care App.

How Purity Affects the Price of Jewelry

The price of gold jewelry isn't just the daily gold rate. You must account for the following:

• Gold Value: (Gold Rate per gram × Weight).
• Making Charges: This covers the labor and design. For 24K coins, this is low (1-3%). For 22K/18K jewelry, it can range from 5% to 25%.
• GST: A flat 3% GST is applied to the total (Gold + Making Charges).

Gold Resale Value: How Purity Affects What You Get Back

Understanding purity is not just important when buying — it directly determines the price a jeweler will offer at resale. Knowing the math protects you from being underpaid.

• The Resale Formula: At resale, jewelers pay only for the pure gold content. For 22K jewelry: Resale Value = (Today's 24K Rate × 0.916 × Weight in grams). Making charges and design costs are not recoverable — they are consumed at purchase.
• 18K vs 22K Resale Comparison: If gold trades at ₹7,500/g today, a 10g 22K piece has a gold content value of ₹68,700. The same weight in 18K is worth only ₹56,250. The purity difference alone is ₹12,450 per 10 grams — a gap that widens as gold prices rise.
• Why Hallmarked Gold Resells Better: BIS-hallmarked jewelry with an HUID code gives the buyer instant confidence in purity. Hallmarked gold typically fetches 2–5% more than unmarked pieces because the buyer can skip independent assay costs. Always insist on hallmarked jewelry.

875, 958, and Other Gold Hallmarks Explained

While 24K and 22K dominate Indian jewelry, you may encounter other hallmarks — especially on imported, vintage, or Gulf-country pieces. Here is what they mean.

• 875 Hallmark (21 Karat): The 875 mark indicates 87.5% pure gold, equivalent to 21 Karats. This purity is the standard in many Middle Eastern countries. If you have jewelry brought from Dubai, Saudi Arabia, or the UAE, the 875 stamp is very common and perfectly valid.
• 958 Hallmark (23 Karat): The rarest everyday purity, 958 means 95.8% gold. It is softer than 22K and nearly as pure as investment gold. Some premium South Indian plain ornaments use this grade for its higher gold content and richer yellow color that is noticeably deeper than 22K.
• 585 Hallmark (14 Karat): 14K gold (58.5% pure) is the global standard in Western markets. In India it appears in designer or export-oriented pieces. At 58.5% gold content, the resale value per gram is significantly lower than 22K — always check the karat stamp before comparing prices.

What is HUID (Hallmark Unique Identification)?

Since April 2023, the Bureau of Indian Standards (BIS) has made HUID mandatory on all gold jewellery sold in India. HUID is a 6-character alphanumeric code laser-engraved on each piece, allowing you to verify authenticity instantly using the BIS CARE app (available on Android and iOS).

How to use BIS CARE to verify your gold:

1. Open the BIS CARE app on your phone.
2. Tap “Verify HUID”.
3. Enter the 6-character code from your jewellery.
4. The app will show the jeweller's name, BIS licence number, karat, and weight.

If a jeweller refuses to show the HUID or claims their gold is exempt, do not buy. All gold jewellery sold through retail channels in India must carry a valid HUID since April 2023. Government-certified gold products (like Sovereign Gold Bonds) are exempt but do not carry a HUID.

How to Check if Your Gold is Real

Before buying, here are quick checks any buyer can do:

• Magnet test: Real gold is not magnetic. If a piece is attracted to a strong magnet, it contains ferrous metal and is not pure gold (though passing this test doesn't guarantee purity — other metals like copper and brass are also non-magnetic).
• Hallmark check: Look for the BIS hallmark and HUID code. Genuine 22K gold should show “916” or “22K” along with the BIS triangle logo. For silver, look for “999” or “925” marks.
• Nitric acid test: A jeweller can apply a small drop of nitric acid to a scratch of the metal on a testing stone. Real 18K+ gold will not react; base metals will turn green or dissolve. Only allow this test at licensed jewellers.
• Density check: Gold has a very high density (19.3 g/cm³ for 24K). A reputed jeweller can measure the density by comparing the weight of the piece in air vs. submerged in water.
• Trust but verify: For significant purchases, request a purity certificate from the jeweller and cross-check the HUID on the BIS CARE app before leaving the shop.