GemCalc – Carat Calculator

Calculate the carat weight of any gemstone — even when mounted in jewelry. No need to remove the stone.
GemCalc is a professional gemology tool designed for jewelers, gold buyers, estate dealers, gemologists, traders, and collectors.
✔️ Works on mounted stones — estimate weight directly on the piece.
✔️ Automatic depth estimation when the stone can't be fully measured.
✔️ Adjustable error margin to fine-tune your estimate.
✔️ Instant and precise carat calculation.
✔️ Built-in densities: diamond, ruby, sapphire, emerald, and more.
✔️ All cuts: round brilliant, oval, pear, marquise, cushion, princess, emerald…
✔️ Measurements in millimeters or inches.
✔️ Available in 12 languages: FR, EN, DE, ES, IT, PT, NL, RU, ZH, JA, KO, AR.
✔️ Premium app, ad-free, one-time purchase.
Perfect for estate jewelry buyers, pawnbrokers, gold dealers, and gemstone traders.