I am reading different articles about this and what I understand is that a UV image of glass can be used to detect the coating. Anyone here knows how to make it possible.
you can use uv sensible camera. The treated side will be black the other one white or less black.
You can also try to expose the sides to UV light, the coated side should be darker to the other one( never try with glass but shoud work and less expensive than the UV camera)