PURPOSE: To identify a jewel, particularly diamond by generating luminescence radiation in accordance with the luminescence spectrum peculiar to the jewel by exciting the jewel.

CONSTITUTION: A light source 10 generates luminescence by exciting a diamond 2 and radiates the luminescence at the luminescence spectrum peculiar to the diamond 2. The intensity of the luminescence generated by exciting the diamond 2 is detected by means of a plurality of photodetectors 18 communicated with a case 8. In addition, the intensity of the light is measured and processed by means of a light measuring system shown as the block 20 in the figure and displayed 22. A filter 14 filtrates the light from the light source 10 so as to remove visible light and an optical system 12 generates parallel rays toward the inlet opening 16 of the case 8 by parallelizing the light from the light source 10. The obtained parallel rays enter the opening 16, reach the table of the diamond 2 through a window 6, and excite the diamond 2 to generate luminescence.