As was established in the previous post, gloss is determined by the amount of light rays being reflected under specular reflection as opposed to diffuse reflection. The more rays reflected through the former method, the glossier the surface is.
|Taktik iPhone case designed by Minimal studio. The surface is described as glossy and although this image is (I suspect) a rendered image, the glossiness of the surface is still conveyed. For quality control, determining the item as meeting the expected gloss level is not acceptable through mere visual inspection (image taken from DesignBoom).|
Gloss could be compared qualitatively by comparing reflection of an image off different surfaces. Surface exhibiting sharper reflection will be considered glossier. But this is only useful in a qualitative way, and only if both surface reflections are distinctly different. Different observant will have different sight and recognition capability as well, so this method is physiologically affected. This qualitative method will not suffice as a quality control method.