... electroplated tool 3.faster engraveing speed LONGXIANG stone engraving bits include A, B, C, D, E , F , G series. Only ... it is better for engraving marble, bluestone, sandstone etc. In general,it is better selected for engraving relieves, good for engraving large characters, ... Chinese Diamond Tools industry. EM12-1210 Diamond Engraving Tool Bit for Carving Stone Marble Granite letter&Relief