Sometimes imperfections are what make natural things beautiful. Natural, untreated blue sapphires are not always top color, but their lighter color and interesting green hues are still beautiful nonetheless.
G - Indian alexandrite under sunlight. Superior brilliance and excellent clarity and although the colour change is not strong, alexandrites from Andrapradesh are well known for their beautiful daylight colour.
Gem quality sphalerite is a rare collector stone. The mineral is usually nearly black in color but is occasionally found in transparent pieces of an orange or yellowish brown hue. Clean pieces are extremely rare.