Carat ↔ Gram Converter
Convert instantly between carats, grams, and milligrams — the standard unit gemstone weight is measured in.
Open Tool → FreeGemstone Weight Calculator
Estimate a gemstone's carat weight from its measurements and specific gravity — useful before you have a scale.
Open Tool → FreeGemstone Identifier (RI)
Enter a measured refractive index — and birefringence, if you have it — to find which gemstone species it could be.
Open Tool → FreeSpecific Gravity Calculator
Enter weight-in-air and weight-in-water readings to calculate SG, then see which gemstone species it matches.
Open Tool → FreeCare & Hardness Lookup
Search any gemstone for its Mohs hardness, toughness, and safe cleaning method before it goes in the ultrasonic.
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Free
Ring Sizer
Calibrate your screen, place a ring on the circle, and find your US ring size 1–16 with diameter and circumference.
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Free
Rough To Cut Yield Estimator
calculate how much polished gem weight you can expect to recover from a raw, rough gemstone.
Open Tool → FreeGemstone Comparator
Compare any two gemstones side by side — hardness, RI, SG, pleochroism — and see which tests tell look-alikes apart.
Open Tool → FreePhoto Color Check
Remove the colour cast from a gemstone photo with a gray card and read the stone's corrected colour. Photos never leave your device.
Open Tool → FreeNatural vs Synthetic Guide
Tick what you see under a loupe and learn what it may indicate about origin and treatment — and what only a lab can confirm.
Open Tool → FreeCarat to MM Size Chart
Find a gemstone's size in millimetres from its carat weight, for any gemstone and cut shape, with ready-made size tables.
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