I've tried that a couple of times just to see.... I didn't see anything really.
I do like to harvest in the dark though. That is, I harvest before the lights come on. I don't wait for any amount of amber trics. When I run sativa dominant strains I find they don't amber easily, some strains don't seem to amber at all. I go for all opaque. With indica dominant hybrids I may find a lot of opaque trics are turning amber and still have a percentage of clear. I won't wait for all opaque or amber and harvest when I think it's done. I've never seen as high as 30-40% amber. That's too late for my taste.