Understanding Gold Karats and Purity
Whether you are looking to sell old jewelry, invest in bullion, or buy a wedding ring, understanding the Karat system (Wikipedia) is essential. A karat (often denoted as 'k' or 'K') is a unit used to measure the purity of gold alongside other alloy metals.
Our gold calculator helps you cut through the confusion. By selecting your item's weight and karat, you can find the intrinsic melt value based on live or custom spot prices. For broader financial planning and valuation tools, explore our other finance calculators.
How is Karat Calculated?
The karat scale goes up to 24. Therefore, 24-karat (24k) gold is considered 100% pure (practically 99.9%). To find the percentage of pure gold in any piece, you divide the karat number by 24 and multiply by 100.
- 24K Gold: 100% pure gold. Highly valuable but too soft for most everyday jewelry.
- 18K Gold: 18/24 = 75% gold, 25% alloy (like copper, silver, or zinc). Premium jewelry standard.
- 14K Gold: 14/24 = 58.3% gold. The most common standard in the US, offering a great balance of durability and value.
- 10K Gold: 10/24 = 41.7% gold. The lowest purity that can legally be marketed as "gold" in the United States.
What is Millesimal Fineness?
While the US and UK primarily use the Karat system, Europe and many international bullion markets use Millesimal Fineness. This system denotes purity in parts per thousand rather than parts per 24.
For example, an 18k gold ring is 75% pure gold. In millesimal fineness, this is stamped as 750 (meaning 750 parts gold out of 1000). A 14k item will often be stamped with 585. Our Karat Purity Conversion tab instantly translates any karat rating into its exact fineness stamp.