Black gemstones can make stunning jewelry, but there are actually very few gemstones that occur in black. The most common is onyx, a variety of chalcedony or cryptocrystalline quartz, which is dyed to produce a uniform black. Onyx is abundant and inexpensive, but it is not what one would call a fine gem.
Back in the Victorian era, a black mineral called jet was very popular, particularly for mourning jewelry. Jet is an organic mineral composed of fossilized wood, somewhat similar to coal. It is very light in weight, so suitable for large pieces of jewelry. But it is also extremely soft compared to other gemstones, with a hardness of only 2.5 to 4.0 on the Mohs scale. Jet is now unfashionable, possibly because of its association with mourning. The fact that it can be burned like coal probably didn't help either.
Some finer gems are occasionally found in black, such as diamond, sapphire and spinel. But the most available high quality black gemstone is tourmaline. Also known by the name schorl, black tourmaline is the most common form of this uncommon mineral. Perhaps 95% of the tourmaline found in nature is black, and this is why black tourmaline is relatively inexpensive, selling at prices well below amethyst or citrine.
Like all tourmaline, black tourmaline is quite hard (7 to 7.5 on the Mohs scale). It has a vitreous, slightly resinous, luster and takes a good polish. Since tourmaline has poor cleavage, it is a very durable gemstone as well.
Black tourmaline is very inexpensive compared to other tourmaline colors and can often be found in much larger sizes. We have cut some black tourmaline over 70 carats. You will find it sold in spheres and cabochons as well as in faceted form, but the faceted pieces display the best brilliance for jewelry.
The lore surrnounding black tourmaline is that it repels negativity and protects the wearer. It is said to be a very good stone to wear when you're experiencing any kind of stress. Placing black tourmaline under your pillow is thought to protect you from nightmares. Placing a black tourmaline at the entrance to your house will protect you from jealous neighbors. Emotionally, black tourmaline is excellent for dispelling fears, obsessions, and neuroses, and bringing emotional stability. Physically, black tourmaline is alleged to strengthen the immune system and help with heart disease, arthritis, and gout.