What "Precious' Gemstone changes color?

Question

In sunlight, this gem is green or bluish-green. In artificial (incandescent) light it is red. By carat weight it is more valuable than a diamond of similar quality. It is found most exclusively in one part of the word. What is it, and where is it found? The first correct answer with the name of the gem and origin gets five stars. The second best answer identifying the gem gets 4 if no one answers all questions.

Answer 1

The alexandrite variety of chrysoberyl was initially identified in the Ural Mountains of Russia in 1830. Alexandrite chrysoberyl from the Ural Mountains is considered some of the best in the world. In addition to Russia, chrysoberyl has been found in Sri Lanka and India, the principal source for this gemstone today. Brazil has produced some excellent alexandrite gemstones. Between 1840 and 1900, Russia was the primary source for alexandrite. During this period, the Takovaya district on the eastern flank of the central Urals was mined extensively and many large emeralds and alexandrites were unearthed. Little specific production information is available but the deposit was thought to be nearly depleted at the turn of the century. No significant amount of new Uralian material has been reported since the Russian revolution in 1917.

Answer 2

Alexandrite/ Named for alexander 2/ Russia

Answer 3

There are 2 style of stone pricious and semi powerful powerful Gemstone :- Emerald,Sapphire,Cat's Eye,Ruby,Blue Sapphire,Yellow Sapphire,Hessonite,Pearl,pink Coral Semi-powerful Gemstone :- Amethyst, Ametrine, Aquamarine, Beer Quartz, Carnelian,Chalcedony, Chrome Diopside, Chrysoprase, Citrine, Ethiopian Opal, Garnet,Iolite, Kyanite, Labradorite,Lapis Lazuli,Larimar, Lemon Quartz, Moonstones, Onyx,Opal,Peridot

Answer 4

Alexandrite...Russia?

Answer 5

opal. Australia.