AGS has given us cut-grading standards for Princess cuts. Designs having pavilions with 2 chevrons came first and, just recently, those with 3 and 4 chevrons. I prefer designs with minimum facets because they give stronger 'bang-bang' on-off reflections/contrast that attract the eye; they also take less time to cut and offer less chance of cutting errors...
Their charts show the grades according to combinations of the slopes of the main facets. We know that this is a good guide – as with round brilliants – but that the 'secondary' facets may contribute significantly to the appearance of the stone.
I saw a broker looking at FireScope or IdealScope image simulations by software to see what these cuts would look like. However, the image he saw will not be what he is getting if the secondary facets are not cut the same way as they are represented in the computer model that is making the image.
There are many ways to cut the facets of a Princess cut. These variations will affect the actual FireScope and IdealScope images and may affect the beauty of the stone in relation to the cut grades.