The Gemray for Windows program is now available. This program is an add-on to the well known Gemcad program. Gemray gives facetors the opportunity to tweak their paterns to take account of factors that are not covered in Gemcad - dispersion , colour and a better display of the effect on tilt on faceted stones. There is a demo on You-Tube ( type Gemray into the search box on the YouTube page.
This looks like being a valuable tool to facetors wishing to get the best result from their faceted stones.
John