When jewelry designers want to add contrast a design, they turn to black stones. Black diamonds are often paired with white diamonds to create a zebra effect in rings and earrings. Black onyx sometimes serves as a backdrop to showcase rubies and emeralds in silver or gold cuffs. Sometimes -- as in the case of the rare black opal -- a necklace is designed around the black stone.
Black opals are by far the most rare and expensive of all opals, fetching upward of $20,000 per carat, according to New South Wales Trade & Investment. The International Gem Society describes black opals as having a "black body color with fire, often spectacular against a dark background." The contrasting color within the opal can also appear dark blue, green or brown. Black opals are used in jewelry as cabochons -- polished domed shapes -- and are usually found in pendants and as centerpieces to rings. Australia is the source of 97 percent of all opals; just a few countries in Africa, South America and Eastern Europe are natural producers. In 2008, NASA added an unexpected opal source to this roster -- Mars. Black opals specifically are found almost exclusively in the Australian town of Lightning Ridge in New South Wales.
Unlike black opals, black tourmaline -- also known as schorl -- is the most common in the wide, rainbow spectrum of tourmalines; 95 percent of all tourmalines in the world are black. The mineral's high iron content is credited for its rich, opaque color; it lacks the translucency found in other tourmaline colors. Because tourmalines naturally form in long, narrow shapes, they're generally cut into facets and are used in all types of jewelry, including necklaces, bracelets, rings and earrings.
Onyx is the most traditional of all the black stones and has been used in jewelry and ornamental design for many centuries. In ancient Rome, soldiers carried banded onyx engraved with images of their heroes for inspiration; during Queen Victoria's reign, onyx was used for cameo brooches; in the Art Deco period, onyx added contrast to ruby and quartz jewelry designs. In modern jewelry, onyx is shaped into beads and cabochons, and -- like tourmaline -- can be found in all forms of jewelry. Onyx continues to be used in cameos and intaglio carvings.
The black diamond, also known as carbonado, differs from traditional -- or white -- diamonds in many ways. Black diamonds are just as hard as white diamonds but endure stress better due to the structural difference between the two. White diamonds are made of solid crystal, while black diamonds are made of millions of conjoined crystals. Black diamonds are thought to be about four billion years old. Mostly found in only two countries -- Central African Republic and Brazil -- black diamonds are much more rare than other diamonds. Most black diamonds used in jewelry design are lab-created -- white diamonds are heated to create the black color. These lab-created diamonds are found in everything from rings and bracelets to necklaces and earrings.
Other Black Stones In Jewelry Design
In addition to these popular stones, other black gemstones that can be found in jewelry design include jet, cassiterite, serendibite, black star diopside, obsidian, tektite, hematite and lodestone. Stones traditionally known in colors ranging from red to violet also have black variations used in jewelry. These include black sapphires, black fluorites, black jaspers, black zirconias, black garnets, black spinels, black moonstones and black beryls, known as emeralds in the green form.