When mounting crystal blanks, crystal blanks can be mounted readily in a desired position on a mounting platform, and during pick-up, they can be readily detached from the mounting platform.;To inspect scratches in a crystal blank 1, diffused oblique light is shined onto the crystal blank 1 from below by light-emitting diodes 6, and light reflected by scratches on the crystal blank 1 is detected by image capturing means 11 directly above the crystal blank 1. The crystal blank 1 is conveyed to the mounting platform 2 by a conveyor robot arm 15, and after inspection, it is conveyed away by same. A plurality of grooves are formed in the mounting surface 3 of the mounting platform 2. Thereby, during mounting, the crystal blank 1 does not slide over the mounting platform 2 and after mounting, it does not adhere tightly to the mounting platform 2. 展开▼