Stone gloss meter is a special instrument for measuring the surface gloss of objects. Widely used in chemical raw materials, coating manufacturing, automobile industry and other supporting special measuring instruments（ Glossiness instrument unit No.2 "Gu"). In the portable glossmeter, 213 is switched to mirror 213 mode, which makes the instrument widely used.

A beam of light emitted by the light source of the stone gloss meter passes through the lens L1 and reaches the measured surface P. the measured surface reflects the light to the lens L2, and the lens L2 converges the light to the photocell at the light bar B. after photoelectric conversion, the photocell sends the electrical signal to the processing circuit for processing, and the later instrument displays the measurement results. It should be noted that in the whole process of glossiness measurement, the light of the default stone gloss meter light source is very stable and will not change.

Glossiness is completely different from the concept of "smoothness" or "roughness" in machining industry, which is aimed at the evaluation of micro roughness of material surface.

According to the measurement principle of stone gloss meter, the light source g emits a beam of light through the lens L1 to the measured surface P. the measured surface P reflects the light to the lens L2, and the lens L2 converges the beam to the photocell at the light bar B. after photoelectric conversion, the photocell sends the electrical signal to the processing circuit for processing, and then the instrument displays the measurement results. According to JIS, the unit of glossiness is% or a number.