Helium help : Comprehensive list of the report parameters
Statistical values

For all parameters that are measured several times (like 8 main crown angles) there are calculated 4 statistical values: minimum, maximum, average and deviation. Deviation of all parameters except diameter is a mere difference between the maximum and minimum values of the parameter. In addition to this deviation, there is a relative diameter deviation parameter that is calculated by the following formula: (Dmax/Dmin - 1) * 100%.

DiamCalc Brilliant Cut Parameters