It has come to our attention that people are buying jewelry set with a gemstone called "Green Amethyst." How strange! to call a gemstone "green purple," which is exactly what this means!
"Green amethyst" is actually "green quartz." Amethyst itself is purple quartz. Gemstones are usually known by their mineral name, such as "diamond," "beryl," or "emerald." Some stones, however, have become known by their color. Amethyst* is one example. It seems silly to me, then, to call green quartz, "green purple."
I think there are two reasons that some people use this name instead of "green quartz": 1) this green quartz is created from heat treating some varieties of quartz, mostly amethyst. This association seems to permit the use of the misnomer. Green heat-treated quartz has its own name, "Prasiolite." 2) A second reason is that many people think of amethyst as one of the nicest of the semi-precious gems; whereas, they don't think of quartz as being very special. It is all around us. It is one of the most plentiful minerals on earth. "Green Quartz" or "Prasiolite" just doesn't have the ring to it that "Green Amethyst" has.
Many of the semi-precious gemstones are actually varieties of quartz, with their own names, such as "Citrine," "Tiger's eye," "Carnelian," "Aventurine," and "Onyx." There are also many semi-precious gemstones that use "quartz" in their names: "Rutilated Quartz," "Rose Quartz," and "Smokey Quartz."
So, why rename "Prasiolite," this particular green variety of quartz which is made by heat treating other quartz? I have a hunch that it is a marketing ploy. "Prasiolite" is unfamiliar to the public. "Amethyst" is February's birthstone; it is a well-known and well-loved gemstone. It is easy and comfortable for jewelry store personnel to say, "This is a green amethyst ring." No explanation necessary. Everyone knows what amethyst is. It gives the prasiolite a boost in recognition, and it gives the nice feeling that it is just like amethyst. But this really isn't fair to our customers.
When I had an occasion to tell a customer that the "Green Amethyst" stone in her ring was quartz, heat-treated to obtain the color, and that the name "Green Amethyst" really means "green-purple," she was understandably upset that this had not been disclosed to her when she bought the ring. She had thought that this was a special, naturally-occurring gemstone, somehow better than an amethyst. It made me sad when I realized that she could have purchased a ring with a truly natural gemstone of a similar color, some shades of peridot, for example, or shades of aventurine.
*Note: The word "amethyst" has become so closely associated with its color, purple, that people believe the word comes from Greek meaning the color purple. Actually, it comes from the ancient Greek meaning "not intoxicated." Hence many of the drinking vessels of ancient Greece were made of amethyst, to protect drinkers from drunkenness!
Sources: Wikipedia, Gem Select (http://www.gemselect.com/other-info/green-amethyst.php)