A property professional with nearly 20 years experience of estate agency in Suffolk and North Essex. During that time I have carried out market appraisals on over 5000 residential properties and have helped over 1500 people successfully sell their home.
Therefore, a son from a color-blind mother (who receives the trait from his mother on the X-chromosome) will always be color-blind, regardless of the state of the father (who can only give his son a Y-chromosome).
Monochromats can match any light with a single primary. They generally have no cones and make all matches using rods. They are very rare, 1 in 10,000,000. With only a single receptor type, they can have no color vision and are truly color blind because they distinguish only brightness levels.