Hi Nadav,

Here the nesting rule applies: If a ray strikes more than one object at the exact same point in space; the last object listed in the NSC Editor determines the properties of the surface or volume at that point.

So, in your case, if both surfaces are placed exactly at the same point in space (and therefore they exists at the ray intercept point), the last surface listed will determine the properties of the surface., so OS will ignore the coating on the green surface.

However, if both surfaces are separated by a distance higher than the glue distance, OS will consider these objects as not in contact and will use the properties of both surfaces:

The Setup Tab > System Group (the Setup Tab) > System Explorer > Non-sequential (system explorer) > Glue Distance In Lens Units: