18K Gold Purity: Percentage, Stamp & Value Guide
18K = 75% gold
18-karat gold contains 75% pure gold by weight — 18 parts gold out of 24.
Step by step
- Purity = karat ÷ 24 = 18 ÷ 24.
- 18 ÷ 24 = 0.75 = 75%.
- Pure gold in 10 g of 18K = 10 × 0.75 = 7.5 g.
18K is the standard for fine jewelry in Europe: rich color with good durability.
Details
- Gold content
- 75%
- Hallmark stamp
- 750
- Pure gold per gram
- 0.75 g
- Pure gold per troy ounce
- 23.33 g
- Pure gold per tola (11.66 g)
- 8.75 g
How it works
A karat (K or kt) expresses gold purity in 24ths, so the karat number divided by 24 gives the gold fraction. Pure gold is too soft for most jewelry, so it is alloyed with copper, silver, zinc or palladium, which also change the color to rose, white or green gold. The price of a gold item depends on its pure gold weight multiplied by the current gold price, plus workmanship.
Nearby values
Related conversions
Frequently asked questions
How much gold is in 18K?
75%.
What is the stamp for 18K gold?
750.
Is 18K gold good for rings?
Yes — it is hard enough for everyday wear.
How do I value 18K gold?
Multiply the weight in grams by 0.75 to get pure gold grams, then by the current gold price per gram.