Color blindness affects approximately 8% of men and 1 in 200 women in the world.
On a rubik's cube or speedcube, the most common confused colors are orange and green (sometimes red). For a colorblind person these colors look a little grey and can be difficult to distinguish if the contrast is not sufficient.
There are many types and degrees of colorblindness, therefore the impact for each individual is different.
For colorblind solvers, we generally recommend cubes with a darker green. Ultimately though, because there are so many degrees we find that is sometimes takes a bit of trail and error to find the cube that a colorblind solver is comfortable with.
The picture below shows the orange green colors on some of our popular 3x3 cubes. Please use this to check with one has the best contrast for you.