Women have a small chance of being born Tetrachromatic, being born with four color cones in their eyes instead of the usual three. It's believed that about 14% of women have Tetrachromacy allowing them to see, supposedly, up to 100x the amount of colors Trichromatic mammals can. People with eye damage to the lens or those who undergo bad laser eye surgery can become semi-tetrachrome since the human lens normally blocks a lot of blue-violet light that allows the reception of ultra-violet light. There people typically have to wear sunglasses outside all the time due to having a strong sensitivity to light.
Humans typically have Red, Green, and Blue color cones. I wish I could find out what Tetras supposedly have but there seems to be limited knowledge about the whole thing.