A gemstone that varies from light pink to deep red, the ruby represents passion, the life force, and prosperity. The deeper and more intense the color, the more precious and expensive the stone.
(Late Latin rubinus, from the Latin rubeus, “red”), a variety of the mineral corundum (Al2O3) distinguished by the replacement of Al3+ ions by Cr3+ ions (from hundredths of a percent to 2 percent). The quantum transitions between the energy levels of the Cr3+ ions split by the crystal field give rise to the ruby’s red color (in contrast to the lack of color of corundum). The laser emission of ruby in the red part of the visible spectrum is related to the transitions between various levels of the Cr3+ ions, while the action of ruby as a quantum mechanical amplifier of radio waves (maser) is related to transitions between spin states.
The ruby is a precious stone of order I. In the USSR, rubies occur in alluvial deposits in the Central and Southern Urals. Outside the Soviet Union, there are important industrial deposits in Burma, Thailand, and Sri Lanka.
Synthetic rubies, obtained by the same process as that used for corundum (but with the addition of Cr2O3), are used in the jewelry and watchmaking industries. They also find use in quantum electronics as the active element of the maser and of the most common solid-state laser, which gives record energies and powers as well as giant pulses.
A. S. MARFUNIN