Austrian Crystal, 50mm Rose AB Pearshape Suncatcher

What is AB – otherwise known as an Aurora Borealis coating – on a crystal prism?

Austrian crystals, made by Swarovski, are colored in various ways, using different metal oxides. A crystal that is perfectly clear but colored has metal oxides mixed in with the lead and silica when the crystal is created. Examples of metal oxides are gold for red, cobalt for blue, or nickel for light green, violet, or blue. Our sapphire or red hearts or stars are examples. 

Very often, a clear or colored crystal is further treated by adding a subtle, extremely fine, colored coating to the crystal. This results from a vacuum process in which the metal oxides are applied to a surface of the crystal, usually the back, or in the case of round prisms, on one portion of them.

A lightly, pastel-colored coating is known as Aurora Borealis, or AB for short. The result is a gorgeous crystal with extra color, sparkle and shine. 

In suncatchers, colored crystals will give the same rainbow display that clear crystals give when in the direct sun. Add the AB coating to a clear or colored crystal and the color display will be even more riotous: rainbows and solid swatches of mauve, aqua, orange.