RapSpecs, short for Rapaport Specifications, are devised by Rapaport to divide diamonds into different qualities for easy reference and sorting.
The RapSpecs in use on RapNet today refer to GIA graded diamonds and take into account a broad spectrum of physical properties of a diamond and reduce them to one number for classification purposes (https://trade.rapnet.com/index.html#/RapSpecs).
RapSpecs are A, B or C and broken down further into divisions (e.g. A1, A2, A3)
All RapSpecs that start with a letter refer to GIA graded diamonds only.
Much of the data that goes into the RapSpec calculation is gleaned from the diamond grading report, and some other data is from the owner of the diamond or from our Rapaport Laboratory (for example brown shade)
Non-GIA grading reports also have RapSpecs, but they are less exact and on a different scale (1, 2 or 3) - see bottom of the page -https://trade.rapnet.com/index.html#/RapSpecs