This research work has presented an investigation on the optimization process parameters on the opal gemstone faceting operation, the machine is available in Bahirdar Poly Technique College but there is no the proper polishing procudures with investigations of optimum process parametres, this research will avoiding such kinds of problems with the specify optimization techniques. The Wollo opal gemstone which is available in Amhara region is the workpiece that investigated the research work. And it presents Taguchi’s Signal to noise ratio and Grey Relational Analysis was applied to improve the multi-response characteristics. the input parameters taken with 3 levels are grit size (600, 1000, 1400 in mesh), speed (30, 60, 90 in m/s) and depth of cut (0.6, 0.8, 1.0 in mm) in the operation to recognize the variants in two performance characteristics those are rate of material removal, and surface roughness value on the work material for faceting the opal gemstone using faceting machine. Material removal rate is calculated using the given formula and SR is measure surface roughness tester. The orthogonal array was chosen to be able to study the effect of mutual interaction between control (input) parameters on the responses. The optimal parametric settings for multi-responses become grit 600 mesh, speed 90 m/s and depth of cut 0.8 mm respectively. Statistically calculated of the Analysis of Variance, grinding speed and abrasive grit size are the most significant controlled process parameters influencing multi-responses at a 95% confidence level in gemstone faceting operation as study when maximization of material removal rate and minimization of surface roughness are concerned. The remaining parameter which is depth of cut does not show significance on responses. Also, the F-test to see which process parameters read F- critical table have significant effect on the quality characteristics. The proposed grey-based Taguchi methodology has been proved to be efficient for solving multi-attribute decision-making problem as a study in gemstone faceting operation. The predicted results were checked with experimental results and a good agreement was found.