Leveridge gauge (shown in the figure with a supplementary device) is one of the most convenient measuring tools used for determination of stone dimensions (including mounted stones).

The measurements are accurate to 0.1 mm with approximate counting of hundredths of a millimeter. Scale range 23.5 mm.

In many cases, the stone size is the only key to weight estimation, which can be carried out with special formulas.

Detailed tables attached to the Laveridge gauge make it possible to determine the carat weight of round and traditional fancy-cut diamonds from their measurements.

To determine the diameter of a stone fixed in A'joure setting, the measurements should be made between the prongs on opposite sides of the stone.

Special device attached to the gauge allows an expert to determine the depth of a stone in any setting, except gypsy setting.

To estimate the stone diameter in a closed setting, find the place of the girdle as indicated by the main crown facets and measure across the opposite crown facets.