This one is so dark purple that it looks BLACK, than a DARK COBALT BLUE when it is held near a light, then it glows a deep purple color when light passes through it! About the beautiful deep amethyst color... This purple color is the result of having manganese in the glass.
Manganese is a mineral, a rock, that was mined, crushed, and pulverized into a powder, then added to vats of molten liquid glass, and acted as a decolorizing agent to turn the natural aqua-tinted glass into a pure crystal clear colorless glass. Then it was blown into a mold to create a vessel or object. But when exposed to the ultraviolet rays of the sun or other sources of UV rays, it triggers a chemical reaction and the manganese starts to oxidize and slowly turns a lavender or amethyst color. The end result is what collectors refer to as SCA (Sun Colored Amethyst) glass. The longer it is in the sun the purpler it becomes.This little insulator reamer was exposed to some concentrated UV rays which had the same affect as the sun, but a lot faster. It has not been colored, stained, or altered. No matter how a glass antique item has turned purple (direct sunlight or UV rays in controlled environment) they all turn the same purple color as it is the same chemical reaction taking place.
The only difference is the time it took to turn purple. What is important is that an item is old enough to turn purple as with few exceptions, only clear glass from before 1915 have manganese in them and will turn SCA.
After this, with the start of WWI, manganese was no longer available as foreign imports decreased and domestic resources turned towards the war effort. Selenium sulphate then replaced manganese as a glass de-colorizer and when exposed to UV rays, it turns a yellow / straw color, and a dark burnt amber color. Generally speaking NO MORE purple glass after 1915! N ot only does this deep purple/amethyst color make this a great looking little insulator, but it also authenticates it as being truly antique, check it out!We put our 30+ years of experience in antiques to use in describing every item we list. This item is in the category "Collectibles\Bottles & Insulators\Insulators".
The seller is "clancy_kid" and is located in this country: US. This item can be shipped worldwide.