Grading
How we describe a stone
Tanzanite is graded on the same four properties as any coloured gem, but colour carries most of the value. We use plain language and publish the measurements, so two listings can be compared without guesswork.
Colour
Hue, tone and saturation. Vivid blue with a violet secondary is the top of the market; pale or greyish material is not listed.
Clarity
Tanzanite is a type I stone: it is expected to be eye-clean. Any visible inclusion is stated and shown.
Cut
Proportions decide how much of that colour you actually see. We favour lively cuts over stones cut heavy to hold carat weight.
Carat
Weight with exact millimetre dimensions, because two stones of equal weight can face up very differently.