14K to 18K table
| 14K weight | 24K gold to add | 18K gold made | Same gold as |
|---|---|---|---|
| 1 g | 0.67 g | 1.67 g | 0.78 g 18K |
| 2 g | 1.33 g | 3.33 g | 1.56 g 18K |
| 5 g | 3.33 g | 8.33 g | 3.89 g 18K |
| 10 g | 6.67 g | 16.67 g | 7.78 g 18K |
| 20 g | 13.33 g | 33.33 g | 15.56 g 18K |
| 50 g | 33.33 g | 83.33 g | 38.89 g 18K |
| 100 g | 66.67 g | 166.67 g | 77.78 g 18K |
Raising 14K to 18K
Added 24K gold = weight × (0.75 − 0.5833) ÷ (1 − 0.75). Ten grams of 14K needs 6.67 g of pure gold and becomes 16.67 g of 18K.
14K and 18K compared
A 10 g piece of 14K contains 5.83 g of gold; the same piece in 18K contains 7.50 g, about 29% more. That is why 18K costs more for the same design.
14K (hallmark 585) is the most common karat in American jewellery: it is harder and more scratch-resistant, and its paler colour suits everyday rings. 18K (750) is softer, more yellow and standard for fine jewellery in Europe.
Calculated with karat ÷ 24 (22K = 91.67%). Hallmarks round slightly differently (916, 750, 585); switch the calculator to the hallmark basis to match a buyer who prices by the stamp.
Frequently asked questions
How much gold do I add to 10 g of 14K to make 18K?
6.67 g of pure gold, giving 16.67 g of 18K.
Is 14K or 18K better for an engagement ring?
14K is harder and wears better on a ring worn every day; 18K has more gold, a richer colour and is less likely to cause reactions in people sensitive to nickel or copper. Both are real gold.
Why is 14K stamped 585 and not 583?
By definition 14K is 58.33%, but the international hallmark standard is 585, set slightly above 14/24 so that a stamped piece is never under-karat.