Don’t use glass shader (it uses refraction which is not needed here). Setup a custom thin sheet glass material instead using layer weight/facing to blend between transparent shader and glossy:
Refraction will typically fail with wrongly setup normals or thin sheet glass.
Transparent shader doesn’t work (easily) with fresnel, hence the layer weight/facing workaround.
Glass material doesn’t have separate controls for refractive and glossy color.
Alternatively it could just be a case of adding glass with a transparency shader. Depending on the model, it might be just the trick, but speedwise you can’t beat the thin sheet glass material described above.