Both rubies and emeralds are minerals, which is a type of rock with ... aluminum in the corundum or beryl crystal when a ruby or emerald forms underground at a high temperature and pressure.

a visitor of the Tucson Gem & Mineral Show. Married couple Kelli and Brian Colgate came all the way from Santa Barbara, California. Besides looking at the the Smithsonian's "Hooker Emerald," the ...