Amethyst is a very purple type of quartz mineral that’s out there.  it’s most commonly purple, but there are other gems that look like this such as sapphire.  It can sometimes be a little more bluish, or reddish, and that’s called a raspberry. 

They can range from a very light lilac color in a lot of cases, to a much deeper, and intense royal sort of purple.  This also is where some of the bluish tones come in. 

They also can be a bit brownish too, or even vivid.  Amethyst is what also shows in some cases as color zoning, which is where there are certain angular areas that are either lighter or darker than the rest of the stone due to the way that light hits the different facets. 

They are used in a lot of jewelry making due to the fact that they have such a wild, vivid color for them. However, many people usually just assume all purple stones are amethyst. 

While there are some variants that look either more reddish or bluish, it’s very rare for them to go outside of these bounds, due to the fact that they’re known for this bright, vivid coloring that brings it out. 

The impurities that are in this are what attribute to a lot of colors. 

As for use, they’ve been around since ancient times, and some Greeks would wear amethysts in order to prevent intoxication whenever they had drink. These stones are found all over the world, so there isn’t one specific location. Due to the nature of them, they also were considered sacred to many different religions and cultures.