Alexandrite has a green to bluish-green color in daylight (relatively blue illumination of high color temperature), changing to a red to purplish-red color in incandescent light (relatively yellow illumination). Green, red, orange and yellow colors. Green, red and orange-yellow colors .
Ordinary chrysoberyl is yellowish-green and transparent to translucent. When the mineral exhibits good pale green to yellow color and is transparent, then it is used as a gemstone. The three main varieties of chrysoberyl are: ordinary yellow-to-green chrysoberyl, cat's eye or cymophane, and alexandrite. Stones that show a dramatic color change and strong colors (e.g. red-to-green) are rare and sought-after, but stones that show less distinct colors (e.g. yellowish green changing to brownish yellow) may also be considered alexandrite by gem labs such as the Gemological Institute of America. Fine-quality alexandrite has a green to bluish-green color in daylight (relatively blue illumination of high color temperature), changing to a red to purplish-red color in incandescent light (relatively yellow illumination). However, fine-color material is extremely rare. Stones that show a dramatic color change and strong colors (e.g. red-to-green) are rare and sought-after, but stones that show less distinct colors (e.g. yellowish green changing to brownish yellow) may also be considered alexandrite by gem labs such as the Gemological Institute of America. This genuine alexandrite gemstone has a very strong color change from deep green in daylight to deep red-violet under incandescent light (100%. colors-this genuine alexandrite gemstone is unheated and untreated). This fine quality natural alexandrite gemstone has a very strong natural color change from bluish green in daylight (see lower portion of photo at left) to a beautiful purple-red color under incandescent light as shown in the upper part of the photo at left (it is 100%. color- Price: $684.50. This natural alexandrite gemstone has a good natural color change from rich green in daylight (see lower photo at left) to a beautiful slightly brownish reddish-purple color under incandescent light as shown in the upper part of the photo at left (it is 100%. color-unheated and untreated). This fine quality natural alexandrite gemstone has a very strong natural color change from bluish green in daylight (see lower portion of photo at left) to a beautiful purple-red In addition to its original discovery in the Ural Mountains of Russia, Alexandrite is found in Sri Lanka, Brazil, and Burma. Synthetic corundums spiked with trace elements that yield an alexandrite-like color change are sold as alexandrite on the gemstone market. These stones have a red-violet, near-amethyst color in incandescent light and a blue-violet color in daylight.  While Russia is the most famous alexandrite source, this stone from Brazil shows beautiful color change from daylight (left) to incandescent light (right). - © GIA & Tino Hammid, courtesy Mayer & Watt. Color. Fine alexandrite is green to bluish green in daylight and red to purplish red in incandescent light. Its color saturation is moderately strong to strong. Stones that are too light do not reach the quality of color intensity seen in fine-quality gems. Cat’s-eye alexandrite, with beautiful chatoyancy along with color change, is extremely rare. This alexandrite has stunning color change with intense colors, and very clean clarity. This color change alexandrite gem was faceted from natural alexandrite rough mined in Brazil. Price: $540.00. This genuine alexandrite gemstone has a fairly good color change from rich green in daylight (see upper photo) to reddish-purple hues under incandescent light (see lower photo). This fine quality natural alexandrite gemstone has a very strong natural color change from bluish green in daylight (see lower portion of photo at left) to a beautiful purple-red color under incandescent light as shown in the upper part of the photo at left (it is 100%. color-unheated and untreated). Alexandrite Color Alexandrite's green hue is a result of chromium impurities. Chromium is the same coloring element found in emerald, the green variety of precious beryl. Sri Lanka (Ceylon) alexandrite is known to exhibit a khaki to brown color change. Chrysoberyl Cat's Eye. Alexandrite is a rare color change and chromium-bearing variety of chrysoberyl. There are a few other chrysoberyl varieties available; most are categorized because of an optical property, such as color, color change effect and chatoyancy. A high clarity rating raises the value of alexandrite, especially one with nice color change like this green to red-purple example. Cat’s-eye alexandrite, with beautiful chatoyancy along with color change, is extremely rare. This alexandrite has stunning color change with intense colors, and very clean clarity. Alexandrite, a strongly pleochroic (trichroic) gem, will exhibit emerald green, red and orange-yellow colors depending on viewing direction in partially polarised light. However, its most distinctive property is that it also changes color in artificial (tungsten/halogen) light compared to daylight. Stones that show a dramatic color change and strong colors (e.g. red-to-green) are rare and sought-after, but stones that show less distinct colors (e.g. yellowish green changing to brownish yellow) may also be considered alexandrite by gem labs such as the Gemological Institute of America.
https://en.wikipedia.org/wiki/Alexandrite https://en.wikipedia.org/wiki/Alexandrite http://www.mineralminers.com/html/alxgems.stm http://www.mineralminers.com/html/alxgems.stm http://www.galleries.com/Alexandrite http://www.gia.edu/alexandrite-quality-factor http://www.mineralminers.com/html/alxgems.stm http://www.gemselect.com/gem-info/alexandrite/alexandrite-gemstone-information-and-education.php http://www.gia.edu/alexandrite-quality-factor https://en.wikipedia.org/wiki/Alexandrite
what color is alexandrite