Gem Quiz: I’m a Gem That Comes Alive at Night

I HAVE BEEN CALLED evening stone because of my intense dislike of sunlight — it does the most terrible things to my coloring, which is usually of a most tender and feminine pink hue. Discovered in 1902 in Southern California (a place that is really too warm for my liking), I was named after a particularly distinguished jeweler and mineralogist from Tiffany’s in New York (ah, New York, a much more pleasant clime). My perfect cleavage makes me a challenge for gem cutters, but if they know what they’re doing they can make my deepest colors shine. Yes, colors with an “s” — I am strongly pleochroic.

Who am I?