The colors of rubies and emeralds are so striking that they define shades of red and green—ruby red and emerald green. But ...

Daniel Freedman, University of Wisconsin-Stout (THE CONVERSATION) The colors of rubies and emeralds are so striking that they define shades of red and green – ruby red and emerald green.

But how can one element – chromium – create the red color of a ruby and green color of an emerald? Rubies and emeralds have the colors they do because, like many substances, they absorb some ...