Hi,
Is there such thing as the same hair-strand having 2 colors? For example can a hair strand be light/goldish blond from the root/base and darker brown or black at the top or vice-versa? Or is a hair-strand always an even 1 tone pigment from root to tip? How would a laser effectiveness be with such hairs?
I can’t figure out if I have short blond hair mixed with coarse dark strands on my chest and stomach, or if they are the same hairs but with 2 tones. I tried looking through magnifying glass on sunlight, and I’m somewhat convinced that my hair is very dark/black at tips but shiny blond at base.
It is likely that you’re looking hair in telogen phase. These hairs have reached the total length is genetically predetermined. The last segment of hair that has appeared on the surface of the skin lacks melanin, this segment is also thinner than the rest (this detail can only be seen under a microscope).
The hairs in this stage are unlikely to be attained by the emission of light.
If the hair at the base isn’t dark and coarse, it wouldn’t work so well, no matter what the color is at the tip.
It might somewhat work, but if it won’t you will know why.
I really hope that you are right that it’s just hairs in telogen phase. I’m planning to start my treatments hopefully this June. I’ve been to 3 clinics and all said that I was a candidate based on how dark and coarse my hair appears, but I never brought to their attention this issue of noticing blond colored hairs at the base of hairs in sunlight.
Pluck a few and post a photo. 
Sounds like telogen hair to me, but if every single hair without exception is like this, then it could be just your hair pattern. If you don’t wax often, then something like 80% of the hairs may be in telogen phase. This is normal. After your first session, all your subsequent sessions will be on fully anagen hair.
Maybe you can better understand the full cycle of hair, watching a video on you tube. It was a project that I conducted for a conference in Zaragoza.
Search for “ciclo del pelo”
Don’t pay for any treatments yet. Do a test spot and see if the hair sheds. If the root is dark, it should work.