Light Observation Day 3

Last night in lab we hung lights, and got to see the differences between all of them. I couldn't help but noticing the the light with the tightest circle (cant remember which one) had an almost glowing blue ring around the outside of it. All of the other lights seemed to wash out and just expand until they faded out. But this light was a nice kept circle, almost held in by the outlying blue glow.