If the smoke ring is low down on the insulator, it could be possible to see it, but if it is way up inside like the one on the bottom pic I posted, I don't like your chance of reading it correctly.
Incandescent flashlight gobes could also interfere withe the colour hue.
The First pic you posted had a lower ring and that's were mine was When readable , Others might not be As Lucky , But When I Pulled it It was Noticeable before I used a Flashlight !