Amethyst and citrine are both verities of Quartz. The difference is color. But natural citrine, with its lovely transparent yellow to orange color, is extremely rare. So almost all citrine on the market is actually amethyst that's been heated to change its color.
Amethyst is the purple variety of quartz and is one of the most popular gems. If it were not for its widespread availability, Amethyst would be very expensive. Amethyst is a widely used gem. Most Amethyst is faceted or cut into cabochons for jewelry. Large chunks of Amethyst are carved. Amethyst is also popular among mineral collectors.
The Color Of Amethyst, has become a coined phrase. Many things are said to be of an Amethyst color. Even other, more expensive purple gemstones are often compared to its color and beauty. It must always be purple to be amethyst. But it comes in a very wide range of purple shades. Amethyst comes in long six sided crystals or can form as druzies that are crystalline crusts that only show the pointed termination's. Its color and nice crystal shapes make it a popular mineral specimen.
Phantom quartz shapes are sometimes present in the interior of quartz crystals, outlining an earlier stage of the crystal's formation. These phantoms are usually composed of other minerals or other varieties of quartz This leaves a coating on most or all of the surfaces of the crystal during its growth. The crystal then resumes its crystallization creating a phantom crystal outline within itself. Some of the crystals we have show these phantoms.