Our cones can already perceive ultraviolet. The lenses of our eyes filter UV out. That is why we are prone to cataracts; the UV light the lens absorbs clouds it

Our cones can already perceive ultraviolet. The lenses of our eyes filter UV out. That is why we are prone to cataracts; the UV light the lens absorbs clouds it over time. People who lack eye lenses have been reported to see ultraviolet as a light, bright purple. Maybe if you had a tetrachromat with no lens, she would see it differently, I don't know.