Free professional-grade calculators for gemologists, cutters, jewelers, and collectors — built by AA Gems & Jewelry. No downloads, works in your browser.
Convert instantly between carats, grams, and milligrams — the standard unit gemstone weight is measured in.
Open Tool → FreeEstimate a gemstone's carat weight from its measurements and specific gravity — useful before you have a scale.
Open Tool → FreeCalculate refractive index from critical angle, or look up reference RI ranges for common gemstone species.
Open Tool →