As someone who's been tested at 70% red/green colorblind, I have often tried to explain to people with normal color vision what it's like to be colorblind. The best explanation I have come up with:

  1. If you give me a box of 8 unlabeled crayons, I can sort them.
  2. If you give me a box of 16 unlabeled crayons, I can sort them.
  3. If you give me a box of 32 unlabeled crayons and good light, I can sort them.
  4. If you give me a box of 64 unlabeled crayons, I'll give you back about 50 piles.

There are some odd effects, like not being able to distinguish some shades of purple from blue due to just not seeing the red component.