A set stone cannot be weighed. Enter its shape, its measurements in millimetres and its gem type: you get the estimated carat weight. Or the other way round, if you are looking for the dimensions of a given weight.
Density used: 3.52 g/cm³
Leave empty: the usual depth for that diameter is applied. Fill it in if you have measured it.
Estimated unit weight
1.00ct
The method is the one used in the trade, and its limits are worth knowing.
Three situations where weighing is impossible, or comes too late.
On the method, its accuracy and its limits.
It is an estimate, typically within 5 to 10 % of an actual weighing. It assumes standard cut proportions; a very deep stone, or one with a thick girdle, will weigh more than the calculation suggests. For an unset stone the scale remains the reference — the estimate is for when weighing is not possible.
Because the carat is a unit of weight, not of size. At identical dimensions a sapphire weighs about 14 % more than a diamond, an emerald about 23 % less. Common conversion charts only hold for diamond: applying a diamond chart to a sapphire is wrong from the first decimal.
For a round stone, the diameter at the girdle. For other shapes, length and width at the girdle as well. Depth is measured from the table to the culet. On a set stone the depth is often out of reach: starting from a target weight then lets you deduce it.
That is the reference correspondence for a round brilliant of standard proportions, and it is very widely used in the trade. But the same one-carat stone may measure 6.3 or 6.7 mm depending on its depth. Diameter tells you about the visible spread, weight about the material: the two are not interchangeable.
Because the weight is distributed differently. A deeply cut stone concentrates its material below the table: it weighs its carat but looks smaller face-up. At equal weight, a spread cut will look larger. It is the classic trade-off between yield and appearance.
Yes, and that is where it is most useful: weighing a 1.2 mm stone on its own makes little sense, whereas calculating from dimensions and multiplying by quantity gives the weight of a whole parcel. It is also where we worked hardest on accuracy. Many conversion charts carry commercially round values (1.0 mm = 0.005 ct, 1.25 mm = 0.01 ct) that overstate pavé stones by 15 to 25 %: reduced to geometry, they imply stones 80 to 90 % deep, which do not exist. Our model is calibrated on stones-per-carat actually measured — you count the stones in a parcel and you weigh the parcel.
The cabochon is offered, with a coefficient suited to its domed form. The estimate is however less precise than on a faceted cut, because dome height varies a great deal from one stone to another.
No. The calculation happens entirely in your browser, nothing is sent or stored. The tool is free to use, with no sign-up.
In Liink, every stone has its parcel, its weight and its traceability: from intake to setting, through to the automatic deduction of stone weight from the metal weight account.
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