Gold price per gram equals the spot price per troy ounce divided by 31.1035. A piece of jewelry is worth its weight in grams times its purity decimal times that per-gram price. Melt value means the worth of pure-gold content alone. Spot price means the quoted market price for one troy ounce of pure gold.
Table of Contents
- From troy ounces to grams
- What karat tells you
- How to calculate melt value
- Why retail and resale differ
- What to weigh before you sell
From troy ounces to grams
According to GoldPrice.com, one troy ounce equals 31.1035 grams, so per-gram price is spot divided by 31.1035 in its gram-price guide. Jewelers and calculators use grams because most jewelry weighs only a few grams. The London Gold Exchange reports that the LBMA Gold Price benchmark is set twice daily in London.
It is set at 10:30 a.m. and 3:00 p.m. through electronic auctions.
What karat tells you
Karat measures purity in parts of 24. The MetalWorthy calculator lists 24K as 99.9%, 22K as 91.7%, 18K as 75.0%, 14K as 58.3%, and 10K as 41.7% in its purity calculator.
Those purities match fineness stamps of 999, 917, 750, 585, and 417. Check the small stamp inside a ring or on a clasp. Use the decimal form in math: 14K becomes 0.583.
How to calculate melt value
MeltValue explains that melt value equals weight times purity decimal times spot price per gram in its melt-value guide. The result isolates only pure-gold content.
A 10-gram 18K chain contains 7.5 grams of pure gold. Multiply 7.5 by the current per-gram price for its melt value.
- Weigh the solid-gold portion in grams.
- Convert karat to a decimal, such as 0.75 for 18K.
- Multiply weight by decimal, then by price per gram.
Why retail and resale differ
Retail price adds design labor, gemstones, overhead, branding, and markup. Resale generally pays only for metal plus wholesale stone value.
Buyer data compiled by TraxNYC and GoldCalcUSA shows scrap buyers pay a percentage of melt, with local shops near 65-80% and refiners near 90-98% before lot fees in its buyer payment data. Get quotes from more than one buyer type.
What to weigh before you sell
Weigh only gold in grams. Subtract stones, non-gold clasps, and springs before calculating.
Exclude plated, electroplated, rolled-gold-plate, gold-filled, and vermeil pieces from solid-gold weight. Bring separated solid pieces and marked karats to the buyer for faster testing.