Dark gray gemstones refer to any gems that have a predominantly dark gray color. Gray gems get their color from the presence of graphite or black pigments within the stone. While black gemstones are more common, dark gray gems are rarer and offer an alternative for those looking for something a bit different than jet black stones. There are a handful of gemstones that naturally occur in dark gray shades and make for interesting jewelry pieces or collector’s items.
Hematite
One of the most common dark gray gemstones is hematite. Hematite is a mineral form of iron oxide that is found in many parts of the world. It has a distinctive grayish black, metallic luster that sets it apart from other gems. The color of hematite can range from silvery and shimmery to almost black.
Hematite rates about 5-6 on the Mohs hardness scale, so it is durable enough for jewelry, but does require some care. In ancient times, hematite was used for carving intaglio and seal stones. Today, hematite is still popular in jewelry and carved gemstone figures. Cabochons and beads are the most common forms of hematite.
Here are some key facts about hematite:
| Chemical Composition | Iron oxide |
| Color | Grayish black |
| Hardness | 5-6 |
| Sources | Brazil, Canada, Russia, Sweden |
The metallic luster and dense black-gray color of hematite make it stand out from other gems. While hematite is not necessarily rare, its dark beauty is mesmerizing.
Black Diamonds
Diamonds come in every color, including black and dark gray. Most black diamonds fall into the gray zone, with dark charcoal or gunmetal tones. There are a few types of black diamonds:
– Carbonado – This polycrystalline diamond aggregate is opaque and dark gray. Carbonados are found through volcanic eruptions.
– Black crystals – Natural black diamond crystals are extremely rare. They form through a combination of inclusions, imperfections, and irradiation.
– Coated – Some colorless or light diamonds are treated or irradiated to turn black.
Like other fancy color diamonds, black diamonds are graded based on the 4Cs:
– Cut – Well-cut black diamonds maximize the intensity of color. Common cuts include round, cushion, radiant.
– Clarity – Black diamonds often have lower clarity due to inclusions. But higher clarity dark gray diamonds are available.
– Carat – 1 carat or higher black diamonds are rare finds.
– Color – Totally black diamonds are exceptionally rare. Most are dark charcoal gray or gunmetal tones.
| Chemical Composition | Pure carbon |
| Color | Black, dark gray |
| Hardness | 10 |
| Sources | Africa, India, Brazil, Canada |
Black diamonds exhibit a mysterious beauty like no other gem. They are sure to make a statement in jewelry or as a collector’s item.
Smoky Quartz
Smoky quartz is a variety of quartz that ranges from light grayish brown to almost black. The smoky color results from natural irradiation within the earth. Significant deposits of smoky quartz come from the Swiss Alps and Brazil, where crystals form in pegmatites deep within the earth’s crust.
The inky gray-brown color of smoky quartz comes from the presence of aluminum impurities. When quartz is irradiated, the aluminum atoms absorb the radiation and make the crystal darken gradually. The longer the crystal is exposed to natural radiation, the darker it becomes. So most smoky quartz is light to medium gray, with the very dark crystals being rare.
Like other quartz, smoky quartz rates 7 on the Mohs scale, making it suitable for any type of jewelry. It is often faceted but also seen as large crystal points for collectors.
| Chemical Composition | Silicon dioxide |
| Color | Light to dark grayish brown |
| Hardness | 7 |
| Sources | Brazil, Switzerland, Scotland, North America |
The natural irradiation process makes each piece of smoky quartz unique. Dark crystals exhibit a deep, smokey allure unlike any other gem.
Black Garnet
Garnets come in every color, and a deep black-gray is quite rare. Black garnets belong to one of these varieties:
– Andradite – Forms in shades of black, gray, brown, yellow, green. Only found in dark hues.
– Melanite – A black variety of andradite garnet. The color results from titanium impurities.
– Schorlomite – An extremely rare black garnet that forms through volcanic processes.
Garnets have a vitreous (glassy) luster when polished. Black garnet exhibits a rich, intense color, especially in larger sizes. These garnets are usually faceted, sometimes carved. Here are the qualities of black garnet:
| Chemical Composition | Calcium aluminum silicate |
| Color | Black, dark gray |
| Hardness | 6.5-7.5 |
| Sources | Africa, India, Canada, Russia, Madagascar |
The deep gray-black tones of these garnets contrast beautifully with white metals like platinum or white gold. Black garnets have a sophistication and rarity that make them treasured in jewelry or gem collections.
Black Opal
Opals are most prized for their shimmering play-of-color. But black opals are the rarest and most valuable variety. These opals form in layers that allow color flashes against a dark background. The body tone ranges from dark gray to jet black. Most black opals come from Lightning Ridge in New South Wales, Australia.
When polished, the play-of-color sparkles brightly against the dark body tone. No two black opals are alike, and the patterns are always unique. Black opals also exhibit an intense level of play-of-color unmatched by lighter opals.
Here are the qualities that determine black opal value and beauty:
| Chemical Composition | Hydrous silicon dioxide |
| Color | Black, dark gray |
| Hardness | 5.5-6 |
| Sources | Australia |
Black opal’s rarity, stunning play-of-color, and dark beauty make it the most valuable type of opal. It serves as the ultimate symbol of Australia’s unique geology.
Obsidian
Obsidian is an igneous rock that forms from molten lava cooling rapidly. It has a glassy texture and fractures conchoidally, meaning along curved planes. Obsidian naturally occurs in several colors, including black, brown, and gray-green. But black obsidian is by far the most common and popular.
Some famous deposits of black obsidian include:
– Yellowstone (USA) – Produces rainbow obsidian with iridescent inclusions along with glossy black.
– Armenia – Early humans shaped Armenian black obsidian into tools and jewelry.
– Mexico – Major source of obsidian artifacts from Mesoamerican cultures.
Although obsidian is not technically a gemstone, its glossy black color gives it an appearance similar to black diamonds or onyx. Obsidian’s glassy texture makes it simple to carve into interesting shapes. And its conchoidal fracture allows skilled artisans to create incredibly sharp edges from obsidian.
| Chemical Composition | Igneous glass |
| Color | Black |
| Hardness | 5-5.5 |
| Sources | Armenia, Mexico, Yellowstone, Greece, Japan |
The glossy black finish of obsidian gives it a beautiful, mirrored appearance. Historically, the rock played an important role as early cutting tools and ritual objects. Today, obsidian remains popular for carvings, jewelry, and arrowheads.
Black Jade
Jade refers to two distinct metamorphic rocks: nephrite and jadeite. Both can form in black or dark olive green colors. The color comes from dense concentrations of iron and magnesium that absorb light. Deposits of black jade exist in Russia, Canada, Wyoming, and China.
When polished, black jade exhibits an attractive waxy or vitreous luster. The dark green-black shades are caused by varying elemental compositions. Black jade is tougher than many crystals, with nephrite ranging from 6-6.5 and jadeite around 7. This makes it suitable for any jewelry or carving use.
Here are the properties that define black jade:
| Chemical Composition | Nephrite: Calcium magnesium iron silicate Jadeite: Sodium aluminum silicate |
| Color | Black, dark green |
| Hardness | Nephrite: 6-6.5 Jadeite: ~7 |
| Sources | China, Canada, Russia, Wyoming |
In Asian cultures, jade symbolizes many desirable qualities like beauty and immortality. For thousands of years, Chinese artisans have carefully craved black jade into ornamental masterworks. Its deep color is mysterious yet sophisticated.
Jet
Jet is fossilized wood that formed millions of years ago from ancient tree parts under extreme pressure. It has an organic genesis like amber but takes much longer to form. Europe and the Middle East offer significant deposits, which humans have used since the Stone Age.
The many microscopic pores and fossilized wood patterns give jet an incredibly smooth, velvety feel. It takes an exceptional polish. While most jet is black, it can occur in brown-black and grayish tones. Jet has a Mohs hardness of 6.5-7.5, making suitable for detailed carvings and jewelry.
| Chemical Composition | Fossilized wood |
| Color | Black |
| Hardness | 6.5-7.5 |
| Sources | England, Asia Minor, Germany, Spain |
Jet has been a popular ornamental material for over 10,000 years thanks to its smooth texture, easy carving, and deep black color. It offers artisans a unique medium. Jet also has an allure that makes it perfect for black jewelry.
Tourmalinated Quartz
While most quartz forms in clear or white, tourmalinated quartz contains black tourmaline crystals running through it. The tourmaline forms thin needle-like inclusions that contrast with the transparent quartz. Darker specimens can appear almost black.
Deposits occur in Brazil, Africa, and North America. The black tourmaline pieces grow slowly within the quartz, so most examples have small hair-like inclusions. But larger tourmaline crystals can form dramatic landscapes inside the quartz.
| Chemical Composition | Silicon dioxide + tourmaline |
| Color | Gray, black |
| Hardness | 7 |
| Sources | Brazil, Africa, North America |
The contrast between the transparent quartz and black tourmaline inclusions makes tourmalinated quartz a rare find for collectors and jewelers. Each piece has a one-of-a-kind look.
Shungite
Shungite is a rare carbon-rich rock only found around Lake Onega in Russia. It contains up to 98% carbon in the form of fullerenes – spherical carbon molecules. This gives shungite its distinctive black color. The carbon content also allows shungite to conduct electricity.
In healing traditions, people revere shungite for its protective energies. Science has confirmed it can neutralize water and emit antioxidants that may benefit health. Other uses include EMF protection, water filtration, and electronics.
| Chemical Composition | Carbon, silicate minerals |
| Color | Black, gray |
| Hardness | 3.5-4 |
| Sources | Russia |
The high carbon content of shungite connects it to diamond in composition, despite its much softer structure. Shungite has grown popular for metaphysical uses and health supplements. But supplies are limited due to its geographical constraints.
Maw-sit-sit
Maw-sit-sit is one of the only gems formed from multiple minerals fused together. It consists of jadeite, albite, chromium-rich kosmochlor, and black minerals like chromite. This combination creates a deep green-black color. Maw-sit-sit forms in northern Myanmar and gets its name from the Burmese words for “jade-stone.”
While maw-sit-sit resembles jade, it rates 6.5-7 on the Mohs scale due to the presence of softer minerals. It takes an excellent polish with a vitreous or resinous luster. With its mix of black and green, maw-sit-sit has a serene yet complex appearance.
| Chemical Composition | Jadeite, albite, kosmochlor, chromite |
| Color | Black-green |
| Hardness | 6.5-7 |
| Sources | Myanmar |
Maw-sit-sit’s rarity comes from its highly specific geological formation. The presence of chromium helps give this “jade” its striking black-green colors. It’s sure to be an intriguing find for gem collectors.
Conclusion
While most people think of deep red or blue gems, dark gray stones have their own allure. Black and gray gems exhibit sophisticated, intense colors that gracefully complement other shades. Many also have ancient histories and spiritual significance.
The rarest black gemstones like black diamonds fetch extremely high prices. But gray-black varieties of quartz, garnet, jade, and tourmalinated quartz offer similar beauty at more accessible price points. They make for memorable jewelry or additions to any gem collection.
Dark gray gems range widely in origin, structure, and composition. Yet they share an elemental beauty that captures the imagination. There’s something primal and powerful about gazing into their midnight tones. Whether set into jewelry or carved into ornaments, these black jewels transmit mystery, romance, and drama. Their darkness gives them a special place in the gem kingdom.
