Abstract: Ruby and sapphire have particular fashion properties such as strong toughness,high hardness,developed parting,abundant colours,variable transparency,obvious pleo-chroism,high refractive index,cat's-eye effect and asterism etc.On the basis of the systematical fashion properties and variety classifications of ruby and sapphire,the technical requirements are elucidated.The skills in the fashing of corundum including cut designing,dividing(sawing),preforming(shaping),cutting(faceting) and polishing are studied emphatically.At last,the appraising standards of the cut quality of gem corundum are probed from the aspects of orientation,shape of cut,proportion,symmetry and polish.