The real beauty of gemstones is revealed only when properly faceted (cut).Only gemstones with right cut and even faceting fetch high prices.
Semi-automatic gem cutting machines has been available for a long time. Only recently a fully automated gemstones cutting and polishing machine has been developed.
Paul Wild GmbH has been using this fully automated machine since early this year. The machine which saves up to 30% of the precious material also grinds with greater precision.
Hand and semi automatic faceting machines can waste up to 60% of the rough gemstones. However experienced gem cutters and lapidaries can determine which type of cut can save most of the uncut weight of the gemstone without compromising the beauty. This is the first time a machine can challenge an experienced gem cutter and even the collective experience in a lapidary.
This machine- a CNC grinding machine with 17 axes, has been in use with the Paul Wild gem cutters near Idar Oberstein. It has processed over 100 rough gemstones into sparking gemstones. Dr. Karl-Heinz Küfer said that the machine first maps the surface of the uncut gemstone. The mapping of the surface is done with narrow bands of light projected automatically unto the uncut stone.Its geometry can be determined by its curvature. Dr. Karl-Heinz Küfer is the head of department at the Fraunhofer Institute for Industrial Mathematics ITWM in Kaisers-lautern, who developed the software for controlling the machine with the help of his colleagues.
After mapping the surface the computer takes about ten minutes to process the image of the gemstone awaiting grinding. Appropriate commands are then sent to the processor control unit. The accuracy of the faceting of 10 micrometers is ensured by the 17 axes which can move the milling head along any desired path.
“With uncut gems of average quality, the system will pay off within a year or two,” Küfer estimates.