Is your partner one in a million and worthy of every “just because” gift? Celebrate your one-of-a-kind love with a beautiful, dark onyx stone. It’s the perfect fashion statement, especially if your special someone likes to turn heads. Want to learn more about this captivating stone? We’re here to tell you more!

What is Onyx?

Onyx may look different than other gemstones, but it actually has some similarities to amethyst and citrine. You’ll often see onyx referred to as a form of “chalcedony,” but that's basically another way of saying tiny quartz crystals! Therefore, all three gems belong to the quartz family.

In their natural form, onyx stones feature parallel layers of colors. Arabic onyx, one of the most common types of onyx, has a black base and a white layer on top. Another variety, sardonyx, is known for a combination of red and white or brown and yellow hues. These parallel layers allow gem cutters to carve unique designs in the top, lighter layer and use the darker color as the background. You’ll also see solid black onyx, but these gems are usually dyed to enhance their color.

Seeking one of those solid black stones? It’s actually fairly difficult to identify gemstones of this shade. So, you’re more likely to come across some kind of onyx alternative, like black spinel or black cubic zirconia.

If you’re looking for authentic onyx, here’s one way to tell the difference. While onyx does shine, it’s not as bright as cubic zirconia. For reference, cubic zirconia ranges between 2.15 and 2.18 on the brilliance refractive index, while onyx only scores between 1.544 and 1.553. If you’re still unsure about the stone you’re eyeing, ask your jeweler for a grading report.

Onyx vs. Black Diamonds

How does onyx compare with black diamonds? First, you should know that these diamonds weren’t even used in jewelry until the late 20th century. Onyx, on the other hand, has been used for centuries.

Much like regular, white diamonds, the black versions are made of carbon vs. quartz (onyx’s mineral). That means black diamonds are more durable than onyx. In fact, all diamonds score a perfect 10 on the Mohs Hardness Scale — a scale that ranks the durability of diamonds, gemstones and other minerals — while onyx only scores a 7. Diamonds also create more sparkle, receiving a rating of 2.42 on the brilliance refractive index.

However, onyx and black diamonds are similar in their stunning, black color — and both stones often receive treatments to enhance it. Black onyx, for example, is created by soaking gray pieces of chalcedony (aka those tiny quartz crystals) in a sugar solution and heating them in sulfuric acid. As a result, small carbon particles sometimes remain in chalcedony’s pores and give off a black tone.

History of Onyx

Records indicate that chalcedony/onyx jewelry was worn in Mesopotamia, the world’s first civilization! Throughout history, onyx has represented different qualities. For example, the stone was reportedly given to ancient Greek sailors to protect them from drowning. And by the 1700s, gem lovers believed onyx had the power to prevent phantoms and evil visions.

But due to its dark color, onyx became a popular stone in mourning jewelry during the late 1800s. It was also thought to zap energy, calm lovers’ passion and bring bad luck.

Thankfully, those bad vibes are in the past! The gem is also associated with removing negative thinking and improving one’s wit, instinct and habits. Today, onyx can be found in various countries across the globe, including Argentina, Australia, Brazil, China, India and the U.S.

Onyx Fun Facts

Onyx is the official stone for celebrating a seventh wedding anniversary!

Onyx might not be as strong as diamonds, but it’s still durable enough for daily wear. In fact, it’s able to withstand bumps, chips and scratches from household dust – a common hazard that often goes unnoticed.

Take extra care when cleaning your black onyx. When a piece is dyed, the black color only seeps a few millimeters into the stone. That means polishing the gem could remove some of its color. Jewelry experts therefore recommend using a soft brush, warm water and mild soap for cleaning.

Mexican onyx (aka limestone onyx or onyx marble) isn’t truly onyx! It’s instead a form of calcite, which is a completely different mineral that’s discovered in limestone caves.

Italian gem engraver Benedetto Pistrucci’s creation, “Venus Marina, Cupid at Her Side,” is one example of onyx work on display at the Metropolitan Museum of Art. The white layer features intricate carvings of Venus and Cupid against the black onyx layer. The entire piece is surrounded by a decorative gold frame.

In his book, “The Curious Lore of Precious Stones,” mineralogist George Frederick Kunz mentioned how the Bahá’i tribes of Myanmar had stone statues in their homes. These statues were created to resemble spirits, and some were crafted from onyx!

Onyx isn’t only used for jewelry. At the Catherine Palace in Russia, the famous Amber Room includes mosaics of marble and onyx. The room was reportedly designed in the early 18th century as a showpiece for Prussian king Frederick I.

The Pokémon character Onix, which is shaped as a chain of gray rocks, apparently gets its name from onyx and “oni,” a term that refers to a magical beast in Japanese folklore.

Sardonyx, the red-white or brown-yellow variety of onyx, was August’s original birthstone before peridot became the popular choice!

This dark, alluring gem is sometimes called “Black Magic.”

Shop Our Favorite Onyx Jewelry

Calia Black Onyx Straight Engagement Ring

Lucia Black Onyx Solitaire Engagement Ring

Claire Black Onyx Split Shank Engagement Ring

Ellison Negative Space Onyx and Diamond Ring

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Gage Diamonds is Chicago's premier jewelry showroom and online retailer of engagement rings, wedding bands, and fine jewelry. We offer a selection of outstanding onyx jewelry, from engagement rings to earrings.

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