All about Karat and Gold Markings

What is a karat? Karat is the measure of purity of gold. Therefore the term KARAT (short: “K” or “Kt.”) describes the purity of gold. In the United States, however, when using the term “karat” to describe the gold content it will be spelled with a k. Not to be confused with the word carat (short: “ct”), which is the term for the measurement of weight for diamonds and gemstones. Therefore karat indicates how much pure gold is in an item. Karat describes the pure gold content of man-made items but also from natural occurring items. While natural occurring items have a karat unit greater than 22, man-made 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:

18 karat gold (also named 18K gold or 18Kt. gold) means that for a piece made of 18K gold were used 18 parts of pure gold for production. 18K gold is the most common jewelry alloy in the US. No other gold alloy has been used so often in the gold production industry.

18 parts of 24 parts are pure gold= 18 times 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 for 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 have to be marked with either “K” or “Kt.” – below we have listed nearly all used gold markings 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 for all karat units

American gold markings (K) Purity International Gold Markings Value per gram
9K 37.5% pure gold 375 $19.31
10K 41.6% pure gold 416 $21.43
11K 45.8% pure gold 458 $23.59
12K 50.0% pure gold 500 $25.75
13K 51.6% pure gold 516 $26.58
14K 58.3% pure gold 583 (Russian gold) $30.03
15K 62.5% pure gold 625 $32.19
16K 66.6% pure gold 666 $34.30
17K 70.83% pure gold 708 $36.46
18K 75.0% pure gold 750 $38.63
19K 79.16% pure gold 791 $40.74
20K 83.3% pure gold 833 $42.90
21K 78.5% pure gold 785 $40.43
21.6K 90.0% pure gold 900 $46.35
22K 91.6% pure gold 916 $47.18
23K 95.8% pure gold 958 $49.34
24K 100% (99.9%) pure gold 999 $51.45

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