I find no difference between each color and when I measure the thickness between colors I find no big difference. Measuring the thickness between points on a specific pick there is a range of thicknesses 1is thin 3 is thickest. That being said all colors work equally well and are a joy to use.
I love these picks and only play with them. They are especially good for flat picking and playing arpeggios as the point helps with accuracy.
The Herdim picks are nice, but I expected more of a difference in thickness between the three colours. Since I'm accustomed to playing with a 3mm pick, they are all very light to me. They do give a much more clear sound than my usual massive pick, so they're added to the box, and I'll use them when they would sound best.
Nice picks. Prompt service. Good value.