This is interresting device, but i am not sure whether the concept based on measuring light reflectivity is valid, because same plastic can be molded in molds w

This is interresting device, but i am not sure whether the concept based on measuring light reflectivity is valid, because same plastic can be molded in molds with different surface structure. May it be mold with mirror finish, or matt sandblasted finish. Also color pigments can be added into the plastic. These things highly affect amount of light reflected from the plastic. And i cannot find how exactly they do their measurements. Would be nice to get more insight.