Camera detection of grease presence on o-rings

Hello all, has anyone had experience here with camera detection of grease presence on an O ring.
I got a process where the operator greases an o ring after it’s fitted on a plastic component. The greasing itself is manual with a brush. I want to then detect with a camera to ensure there is grease present.

I am a bit worried if this can be reliably done (especially since it is greased manually). I suppose the colour of the grease is key here?

Thanks everyone in advance :slight_smile: