5.50cwt Ruby/Sapphire Mixed Lot

5.50cwt Ruby/Sapphire Mixed Lot
Ruby & Sapphire mix	5.50cts (scale not included)	Bottom view rubies & sapphires

   ITEM DESCRIPTION

Pure Corundum (Al₂O₃) is rare in nature and is perfectly colorless. Small amounts of metalic elements can substitute for aluminum in the corundum crystal structure, giving rise to many color variations. Gem corundum of any color is refered to as sapphire with a preceeding color designation if the color is any other than blue. Blue corundum is simply called sapphire. There are two other color varieties of corundum that have specific names, the pinkish-red to red ruby and the orangish-pink padparadscha.

The famous pinkish-red to red ruby owes its color to chromium (Cr³⁺) impurities, and the color of the rare orangish-pink padparadscha sapphire is from both iron and chromium impurities. The color of the well known blue sapphire (or simply sapphire) is due to Fe²⁺ and Ti⁴⁺ impurities. Iron in the Fe³⁺ state causes the color in some yellow sapphires, while other yellow sapphires owe their color to irradiation induced 'color centers'. Other color influencing impurities in sapphires are vanadium, cobalt and nickel.

Some sapphires owe their color to 'color centers' which are not fully understood, but it can be said that they are created by radiation and destroyed (reversed) by heating or in some cases by exposure to light. Some color centers in sapphire are stable until heated hundreds of degrees while others are very unstable, fading within a few days merely by exposure to light.