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

and it has an atomic radius of 0.130 nm. At room temperature Chromium has a bcc (body-centered-cubic) crystal structure with a basis of one Cr atom. The unit cell is illustrated. E = 248 GPa.

But add a dash of chromium, and they become ruby, emerald and alexandrite. The chemist's tool of crystal-field theory, which models the electronic structure of transition ... the biggest obstacles to ...