ASTM D523-14 (2018) is a standard test method on specular gloss for the measurement of Glossiness of Non-metallic specimens at 60 °, 20 ° and 85 ° geometries. This method evaluates the Glossiness grade by comparing the specular reflectance of the specimen with the black Glass standard, which is associated with visual observations. The resulting measurement of Glossiness is affected by the surface refractive index of the specimen, so samples with similar surface refractive index are usually selected when comparing specimens. In addition, this standard also states that Glossiness is closely related to the Miscellaneous visual characteristics of the specimen surface Appearance, such as the sharpness of the reflection image and the reflection haze. Although the relationship between the Glossiness value and the perceived interval is not fully understood, this test method provides an instrumental scale with laboratory repeatability in the evaluation of coating specimens, which can be consistent with the visual evaluation.