Think in twenty-four parts
Karatage expresses gold as a share of 24 parts by mass. In the ideal model, 24K is pure gold; 18K contains 18 parts gold and six parts other metals.
Convert a real weight
For a 10-gram metal item, 21 ÷ 24 × 10 gives 8.75 grams of fine gold. The remaining 1.25 grams is other metal. Stones and non-metal components should be excluded first.
Read the actual fineness
A fineness mark expresses precious-metal content in parts per thousand. Actual stamped or assayed fineness can differ from the ideal karat fraction; use the product’s specification for a real valuation.
Separate metal value from jewellery value
Design, craftsmanship and retail charges are separate from fine-gold content. A theoretical melt-value calculation does not tell you what a shop will pay.
Sources & further reading
Sources checked 13 November 2026. These organisations provide reference material and do not endorse this website.
