Alexandrite is known as "Emerald by day, ruby by night" because it has one of the most dramatic color changes among gemstones, such as green in sunlight and red in incandescent light. The very precious habit of alexandrite color change is caused by the presence of minor impurities in the element chromium. The most desirable Alexandrite colors are those that have a very clear color change.
Zultanite is a precious mineral from the Diaspora that is mined in the Albir Mountains in southwestern Turkey. The color of Zultanite varies between yellowish green, light gold and purple pink, depending on its light source.
yellow sapphire is a gem of the corundum family and is a twin of ruby and blue sapphire. it is available in yellow, golden and orange colors. the highest quality is known to be of lemon-yellow color. the color in yellow sapphire is of iron and titanium.