Gold purity calculation guide
18k Gold Value per Gram: How to Estimate Raw Gold Content
Eighteen-karat gold is 75% pure. A raw value-per-gram estimate converts gold’s troy-ounce price into grams and applies the 18/24 purity factor.
18k gold purity and 750 fineness
The purity calculation is 18 ÷ 24 = 0.75, or 75%. A 750 mark represents the same approximate fineness.
Stamps can be inaccurate or apply only to part of an item, so testing may still be needed.
18k gold value per gram formula
Divide the selected gold price per troy ounce by 31.1034768 for pure-gold value per gram, then multiply by 0.75.
Multiply that 18k per-gram estimate by the item’s gold-alloy weight after excluding stones or non-gold components where possible.
Raw value vs real market value
An actual payout can account for testing, refining, solder, clasps, stones, risk, and buyer margin. It may therefore be below arithmetic melt.
A finished jewelry item may also have brand, design, antique, or resale value beyond contained gold.
Calculate an 18k item
Use the Gold Karat Value Calculator and select 18k to estimate purity, pure-gold weight, and raw metal value.
Physical metals research
Compare Raw Gold Value with Bullion Pricing
If you are comparing jewelry or scrap-gold value with investment-grade physical gold, review current coin and bar pricing separately. Bullion premiums and dealer terms are not included in a jewelry melt-value estimate.
View Physical Gold PricingAffiliate disclosure: SilverGoldInvestor.com may receive compensation if you visit or purchase through this link. This article is educational and does not recommend JM Bullion, any specific product, or physical metals as suitable for every reader.