All about Karat and Gold Markings

What is a karat? The term “karat” (short: “K” or “Kt.”) describes the purity of gold—not to be confused with the word “carat” (short: “ct”), which refers to the weight measurement of diamonds and gemstones. Karats are used to indicate how much pure gold is in not only manmade items but also naturally occurring items. While naturally occurring items have a karat unit greater than 22, manmade items have a karat unit between 1 and 24. The most common karat units in the US are 10K, 14K, 18K, and 24K. “24 karat” became the mark used to indicate that an item is made of pure gold.

To understand the idea of karat to indicate the purity of gold, you have to imagine pure gold as a whole pie which can be divided into 24 equal slices. Each karat equals one slice of the whole pie. Therefore, 24 karat is 100% gold – pure gold. According to this calculation 1 karat stands for 4.166666% pure gold.

Let’s turn our explanation into a real calculation:

A piece that is 18-karat gold (also called 18K gold or 18Kt. gold) means 18 parts of pure gold were used for production. Eighteen-karat gold is the most common jewelry alloy in the US. No other gold alloy has been used so much in the gold production industry.

18 of 24 parts are pure gold = 18 x 4.166666% = 74.999988% = 75% rounded up = 18K gold

Most common gold alloys in the US:

  • 14K gold – contains 58.5% pure gold
  • 18K gold – contains 75.0% pure gold
  • 22K gold – contains 91.6% pure gold
  • 24K gold – contains 99.9% pure gold

Gold Markings – An Overview of Common Markings in the US

The US Federal Trade Commission (short: FTC) has standardized the gold markings since the 1940s. Under these regulations, items 10K or greater must be marked with either “K” or “Kt.” Below, we’ve listed nearly all gold markings used for items made of 10K, 14K, 18K, 22K, and 24K gold.

Karat Purity Gold Markings Current Value
10K 41.6% pure gold 10K gold stamp $490.04 per ounce
14K 58.5% pure gold 14K gold stamp $691.35 per ounce
18K 75.0% pure gold 750 gold stamp $886.35 per ounce
22K 91.6% pure gold 916 gold stamp $1,082.52 per
24K 99.9% pure gold gold marking coming soon $1,178.07 per

More about the current value: gold price per pennyweight, gold calculator

Overview of All Karat Units

American Gold Markings (K) Purity International Gold Markings Value per gram
9K 37.5% pure gold 375 $25.83
10K 41.6% pure gold 416 $28.65
11K 45.8% pure gold 458 $31.55
12K 50.0% pure gold 500 $34.44
13K 51.6% pure gold 516 $35.54
14K 58.3% pure gold 583 (Russian gold) $40.16
15K 62.5% pure gold 625 $43.05
16K 66.6% pure gold 666 $45.87
17K 70.83% pure gold 708 $48.77
18K 75.0% pure gold 750 $51.66
19K 79.16% pure gold 791 $54.48
20K 83.3% pure gold 833 $57.37
21K 78.5% pure gold 785 $54.07
21.6K 90.0% pure gold 900 $61.99
22K 91.6% pure gold 916 $63.09
23K 95.8% pure gold 958 $65.98
24K 100% (99.9%) pure gold 999 $68.81

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