16 Black Gemstones (How Many Do You Know?)
Some black gemstones are so well-known their names have become synonymous with the color black. Others are less well-known by the gem buying public, and some consumers may be unaware particular gem species even occur in black. How many of these 16 black gemstones do you know?
12 Minute Read
Is Black a Color?
Technically, black isn't a color. Gemologists describe color in terms of hue, tone, and saturation. Hues, such as red, blue, green, etc, are what most people commonly call colors. However, terms like black and white actually refer to tone, the relative darkness or brightness of a hue. Black is the darkest tone a gem can have. Regardless of the technical definition, most gem enthusiasts and professionals in the trade use the term "black" as a color when describing gemstones.
Diamonds can get their color in several ways. Chemical impurities are the most common means. For example, the presence of nitrogen generally makes diamonds yellow, while boron turns them blue. Alternatively, exposure to radiation famously turns diamonds green. Black diamonds get their color differently, from numerous inclusions within the stones.
Unlike chemical impurities, inclusions aren't part of the structure of the diamond on an atomic level. Instead, they are tiny specks within the stone. These inclusions are mostly black graphite. A soft form of carbon, graphite forms when the Earth's pressure isn't powerful enough to create diamond. Black diamonds have so many tiny graphite crystals clouding their body that the diamond appears black. However, strictly speaking, the graphite is black, not the diamond itself. Although this process occurs naturally, some producers irradiate natural black diamonds to amplify the graphite in their crystals. This deepens the apparent black color.
While black diamonds still have diamond's famous hardness of 10, the presence of so many inclusions weakens their crystal structure. Although no natural material can scratch them (except other diamonds), these stones may split with less force than other diamonds, and their surface will appear pitted. Black diamonds are certainly beautiful, but wear them with care and use protective settings.
What are Carbonados?
Although frequently called "black diamonds," carbonados are a polycrystalline material composed of amorphous carbon, graphite, and diamond. (Diamonds typically used in jewelry, including black diamonds, are crystalline). This unusual material has even greater durability than crystalline diamond but is primarily used in industrial applications. However, in 2022, Sotheby's sold a 555.55-ct faceted carbonado for more than four million US dollars.
The name "black sapphire" is often used to describe any ultra-dark sapphire gem, whether blue, brown, or green. Since the darkest sapphires don't allow much light to travel through the crystal, they look black unless you shine a strong light through them. Although rare, true black sapphires do occur naturally, usually in Australia.
Some black sapphires with precisely aligned rutile inclusions may display asterism. This "star-stone effect" shimmers across the surface of the gem. Gem faceters can cut these sapphires into rounded cabochons to highlight six or twelve-pointed stars. Unfortunately, as in black diamonds, abundant inclusions may compromise the integrity of the sapphire, leaving it especially vulnerable to breaking. Star sapphires are a really exciting gemstone to wear, but handle them with care and use protective settings.
Black Tourmaline (Schorl)
Most gem lovers are familiar with the bright blue of paraíba tourmaline or the powerful green of chrome tourmaline. Many don't know that the schorl variety of tourmaline can have a beautiful black color. Schorl gets it color from high levels of iron and its name from the German village where the first samples were identified. Historically, gem cutters used faceted schorl extensively in mourning jewelry. Although not well-known to the general public today, beautiful raw schorl crystals will command high prices from collectors. You can still find some faceted gems, but polished stones or carved beads are the most popular ways to use schorls in jewelry today. With a hardness score of 7-7 ½, any tourmaline jewelry is suitable for daily wear.
Like tourmaline, spinel is famous for bright hues but can also occur in black.
Spinel can take a very high polish, making these black gemstones especially reflective and shiny. With a hardness score of 8, spinel has excellent resistance to scratching, so it will maintain its polish even with regular wear. Fortunately for budget-conscious consumers, black isn't the most popular spinel color. Therefore, black spinels have lower price-per-carat costs than other spinels. You can make a bold statement for less money.
Black Garnet (Melanite)
A subset of the rare andradite variety of garnet, melanite is the only black garnet, due to traces of titanium oxide in its composition. Named after the Greek word melanos for "black," melanite was popular during the Victorian Era as a mourning gem. While other colors and types of garnet saturate today's market, melanite gems are scarce. Don't expect to find melanites in just any jewelry store.
Unlike in many other gem species, black color in opals will command the highest prices. But to be clear, the black in black opal refers to the body color. Against this background, opal's famous play-of-color effect can look especially astounding.
There are three sub-categories of black opal: semi-black opal, gray-base black opal, and black crystal opal. All these opals must appear black under reflected light but may actually be dark gray, green, brown, or blue. Black crystal opal, the most desired type, is distinguished by its transparency to semi-transparency and exceptional play of color. The most famous source of black opal is Lightning Ridge in Australia.
All opals require extra care. They have great sensitivity to sudden changes in temperature and are vulnerable to fractures and scratches. Consult our opal care guide for wear and maintenance guidelines. Protective settings for opals are a must, especially for ring use.
Black Jade (Jadeite and Nephrite)
Jade is an umbrella term that includes both jadeite and nephrite. Each of these distinct minerals can occur with natural black color. Since black isn't highly desired in jade, black jade has a relatively low price, far lower than the coveted green and lavender jade.
Jade often forms in massive boulders. As a result, gem cutters can sometimes carve rings and bracelets from a single block. Such single-stone pieces are called hololiths.
A naturally occurring black glass, obsidian forms as a result of volcanic activity. As such, obsidian pieces may include trapped air bubbles and appear very shiny. When fractured, obsidian pieces can have extremely sharp edges — sharper than modern surgical blades.
Obsidian pieces may be completely black or incorporate bands of other colors like purple, green, gray, and orange. "Snowflake obsidian" even has white patches. Nevertheless, the term "obsidian" has become a popular descriptor for the color black.
A relatively unknown gemstone, diopside can have a natural black color and makes a very pretty jewelry stone. Diopsides can potentially show one of two phenomenal effects: asterism or chatoyancy, the "cat's eye effect." In black gemstones, these effects are quite striking. Star diopsides will show four rays more often than six. They're also distinctive because one arm will be sharp while the other will be less defined.
A common type of quartz, chalcedony has an internal structure made of extremely tiny cryptocrystalline pieces. These crystals are so small that chalcedony both appears and feels very smooth. Because chalcedony is so abundant in nature, you can find this gem in many colors and patterns, including black.
Interestingly, some confusion exists within the trade over black chalcedony. Solid black chalcedony with no other colors should just be called "black chalcedony." However, many call solid black chalcedony "onyx." Although onyx with black and white bands, also called "Arabic onyx," is very popular and distinctive, this name should not be applied to solid black chalcedony.
The term "onyx" should refer only to chalcedonies with straight or nearly parallel layers of color. Furthermore, onyx varieties can have red, brown, yellow, and blue layers, not just black and white. These contrasting layers have made onyx a traditional favorite for cameo carvings. (Agate, another variety of chalcedony, has concentric or curved bands of color).
To add more confusion to the mix, sometimes onyxes are dyed solid black, and most black chalcedony on the market is actually dyed.
Hematite is a black stone whose name derives from a Greek word for blood. (Rare red and gray hematites may also occur). Since this mineral is an iron oxide, its surface will rust over time, becoming a dark reddish color. In fact, hematite crystals contain so much iron they will feel quite heavy for their size. Due to hematite's density and tendency to fracture, you will most often find it shaped into beads or set securely in signet rings with fashionable intaglio carvings. Fortunately, hematite is one of the most affordable of all black gemstones.
The next five black gemstones are all organic in origin. This means they were naturally created by living organisms. First, we'll look at black pearls, which grow within the bodies of some mollusk species in both saltwater and freshwater conditions.
Pearls that form in nature without human intervention rarely show black color. However, cultured Tahitian pearls can have a truly black body color. Some pearls, especially lightly colored, inexpensive freshwater pearls, may receive treatments of silver nitrate dye or gamma-ray radiation to create black body colors.
Created from buried wood logs impregnated with natural oils, jet is stronger and smoother than coal, which forms in a similar manner. Nevertheless, jet is still notoriously soft. As a soft, opaque material, jet usually appears in jewelry as carvings or beads. Since jet is basically condensed and oiled wood, gems feel light and warm to the touch.
Gem-quality jet occurs in a few places around the world, but the most famous source is Whitby, England. Archeological evidence shows that people at that location used jet as an ornament even in Neolithic times. However, the popularity of jet skyrocketed in the 1860s in the United Kingdom, when Queen Victoria wore it as a mourning gem following the death of her husband, Prince Albert.
Jet is one of the most well-known black gemstones, and "jet black" has become a popular color description.
When someone mentions coral, you probably think of a bright, pinkish orange color or perhaps an exotic blue hue. However, black coral also exists, and black coral reefs are found off the coasts of Hawaii and Queensland, Australia. Both locales have enacted laws restricting (and sometimes banning) the exportation of black coral to protect their endangered reefs. As such, most coral jewelry you will find (black or otherwise) will likely be vintage.
Black coral is a type of protein-rich conchiolin coral. You may hear it called "king's coral" or "Akabar coral." Despite its rarity, black coral isn't the most valuable color for conchiolin coral. Gold is the most prized color, which has led to some dealers bleaching black coral.
The hardened resin of ancient trees, amber most often occurs in yellow, brown, or reddish colors. It also famously traps and preserves prehistoric vegetation and bugs. Archeological evidence shows that humans have been using amber for at least 10,000 years, not only for ornamentation but also for practical purposes, such as burning it as incense. In fact, the German name for amber is bernstein, which literally means "burn stone."
While amber doesn't start black, it can darken significantly due to oxidation if its outer layer is removed by polishing or cutting. Amber is notoriously porous and soft, even when unaltered. You may also find amber gemstones that have been dyed black.
The primary source of amber is the Baltic Sea in Europe, but there are other gem-quality deposits as well.
Humans have used animal horns as adornment for many millennia, but conservation laws now greatly restrict their use. Most horn is yellowish to brown, but some dark examples are almost black. You may find vintage jewelry that features large, polished horn pieces.
Emily Frontiere is a GIA Graduate Gemologist. She is particularly experienced working with estate/antique jewelry.
International Gem Society
Choosing Pearl Engagement Ring Stones
How Can Gem Buyers Protect Themselves from Fraud?
Choosing a Ruby Engagement Ring Stone
Gem Trends 2018: Ultra Violet Gems and More
What is the Best Lap for Polishing Sapphire?
Seven Famous Pearls and Their Histories
Opal Stones and Gems: Value, Price, and Jewelry Information
Seven Stunning but Delicate Engagement Ring Stones
When you join the IGS community, you get trusted diamond & gemstone information when you need it.
Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!