Gold Purity Weight Converter

Gold karat conversion, diamond size and sieve references, and guides to diamonds, emeralds, rubies and sapphires. Seven languages. For approximate guidance.

A bench reference for jewelers and goldsmiths: estimate gold weight across supported karats and explore diamond and coloured-stone reference information.

Enter a piece’s current karat and weight, choose the target karat, and set a manufacturing loss percentage. The app shows an estimated converted weight for approximate planning guidance; actual finished weight may vary.

GOLD CONVERSION • Supported karats: 24K, 22K, 18K, 16K, 14K, 12K, 10K, 9K and 8K • Compare estimated weights across supported karats • Apply your own manufacturing loss percentage or a saved manufacturer’s usual figure • Yellow, rose and white gold, with nickel- and palladium-alloyed white gold treated separately • Adjust reference densities in Settings to reflect your supplier’s figures • Save pieces by ID and reopen them when signed in • Use the calculator without creating an account

DIAMOND SIZE AND SIEVE REFERENCES • Convert millimetres to estimated carat weight, and back, for ten diamond shapes • Look up approximate sieve reference diameters for round stones • Carat describes weight, not size: these estimates are for guidance, and only weighing a stone establishes its carat weight

GEM REFERENCE • Diamond, emerald, ruby and sapphire: colour, clarity, inclusions, treatments and origin • Diamond colour illustrations for the near-colourless range and fancy colours • Bench warnings for treated stones, including fracture-filled diamonds, lead-glass-filled rubies, oiled emeralds and diffused sapphires

REFERENCE LIMITS Calculated weights, size and sieve references, and colour illustrations are approximate guidance. The app does not measure, weigh, grade or identify stones, and it does not replace a laboratory report or a supplier’s own figures.

Colour illustrations are educational and vary by screen. They cannot be used to match or grade a real stone. The gem reference is not affiliated with or endorsed by any gemological laboratory.

SEVEN LANGUAGES English, Traditional Chinese, Simplified Chinese, Thai, Vietnamese, Japanese and Korean.

A practical reference for everyday work at the jewelry bench.