Onyx Gemstone Beads
Black Onyx is highly esteemed in the world of gemology for its rich, deep color and fine crystalline structure. Scientifically, Onyx is a variety of the silicate mineral chalcedony, formed by the deposition of silica at low temperatures in gas cavities in lava. This results in its unique bands of color, which can range from white to almost every other shade, often layered in striking, contrasting patterns.
Facts: Black Onyx has been used since antiquity, cherished not only for its beauty but also for its purported protective properties. The Romans, in particular, crafted seals, amulets, and rings from Onyx. It was also popular amongst the Greek and Egyptian civilizations for stone carvings and cameos, where its layered colors were ideal for creating images with depth and contrast.
Metaphysical / Holistic: Black Onyx is believed to bring strength, endurance, and perseverance to those who wear or carry it. It is also thought to help individuals face their fears and build self-confidence.
Onyx 10mm Round Step Cut - 15-16 Inch
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$18.00
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$18.00
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$18.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all to black stone, and much of the black Ony...
View full details
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$18.00
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$18.00
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$18.00
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$18.00
MATTE Onyx 10mm Round - 8-Inch
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$9.00
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$9.00
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$9.00
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$9.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$9.00
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$9.00
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$9.00
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$9.00
MATTE Onyx 8mm Round Large Hole 8-Inch
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$14.00
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$14.00
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$14.00
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$14.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$14.00
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$14.00
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$14.00
$14.00
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$14.00
Onyx 10mm Round Large Hole 8-Inch
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$14.00
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$14.00
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$14.00
$14.00
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$14.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$14.00
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$14.00
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$14.00
$14.00
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$14.00
Onyx 6mm Round Faceted 8-Inch
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$9.00
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$9.00
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$9.00
$9.00
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$9.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$9.00
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$9.00
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$9.00
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$9.00
MATTE Onyx 4mm Round - 8-Inch
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$6.00
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$6.00
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$6.00
$6.00
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$6.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$6.00
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$6.00
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$6.00
$6.00
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$6.00
Onyx 12mm Square 8-Inch
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$11.00
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$11.00
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$11.00
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$11.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$11.00
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$11.00
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$11.00
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$11.00
Onyx 12mm Coin 8-Inch
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$11.00
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$11.00
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$11.00
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$11.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$11.00
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$11.00
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$11.00
$11.00
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$11.00
Onyx 8mm Star Cut Round 15-16 Inch
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$19.00
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$19.00
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$19.00
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$19.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$19.00
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$19.00
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$19.00
$19.00
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$19.00
Onyx 4mm Rondelle Faceted 8-Inch
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$16.00
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$16.00
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$16.00
$16.00
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$16.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$16.00
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$16.00
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$16.00
$16.00
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$16.00
Onyx 6mm Rondelle 8-Inch
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$11.00
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$11.00
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$11.00
$11.00
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$11.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$11.00
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$11.00
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$11.00
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$11.00
Onyx 8mm Faceted Rondelle 8-Inch
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$14.00
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$14.00
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$14.00
$14.00
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$14.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$14.00
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$14.00
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$14.00
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$14.00
MATTE Onyx 30X40 Rectangle 8-Inch - CLEARANCE
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$21.00
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$21.00
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$21.00
$21.00
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$21.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$21.00
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$21.00
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$21.00
$21.00
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$21.00
Onyx 6mm Faceted Rondelle 8-Inch
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$14.00
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$14.00
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$14.00
$14.00
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$14.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
Original price
$14.00
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$14.00
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$14.00
$14.00
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$14.00
MATTE Onyx 10x14 Oval 8-Inch
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$11.00
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$11.00
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$11.00
$11.00
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$11.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
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$11.00
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$11.00
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$11.00
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$11.00
Onyx 40mm Square Donut - Pendant
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$9.00
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$9.00
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$9.00
$9.00
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$9.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all to black stone, and much of the black Ony...
View full details
Original price
$9.00
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$9.00
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$9.00
$9.00
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$9.00
MATTE Onyx 12mm Coin 8-Inch
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$11.00
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$11.00
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$11.00
$11.00
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$11.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
Original price
$11.00
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Original price
$11.00
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$11.00
$11.00
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$11.00
Onyx 7x8mm Faceted Rice Bead - 15-16 Inch
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$18.00
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$18.00
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$18.00
$18.00
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$18.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all to black stone, and much of the black Ony...
View full details
Original price
$18.00
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Original price
$18.00
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$18.00
$18.00
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$18.00
Onyx 8mm Faceted Rondelle Large Hole 8-Inch
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$19.00
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$19.00
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$19.00
$19.00
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$19.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all-black stone, and much of the black Onyx o...
View full details
Original price
$19.00
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$19.00
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$19.00
$19.00
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$19.00
Green Onyx 8x11mm Leaf - 8 Inch
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$95.00
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$95.00
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$95.00
$95.00
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$95.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all to black stone, and much of the black Ony...
View full details
Original price
$95.00
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Original price
$95.00
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$95.00
$95.00
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$95.00
Onyx 8x11mm Leaf - 8 Inch
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$95.00
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$95.00
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$95.00
$95.00
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$95.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all to black stone, and much of the black Ony...
View full details
Original price
$95.00
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Original price
$95.00
Original price
$95.00
$95.00
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$95.00
Red Onyx 8x11mm Leaf - 8 Inch
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$95.00
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$95.00
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$95.00
$95.00
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$95.00
Onyx is a black and white banded Chalcedony, a cryptocrystalline Quartz. It is often thought of as an all to black stone, and much of the black Ony...
View full details
Original price
$95.00
-
Original price
$95.00
Original price
$95.00
$95.00
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$95.00
About this stone
Color
BlackWhiteBanded Black-and-White
Origin
MexicoPakistanBrazilMadagascarUruguay
Mohs hardness
6.5–7
Treatment categories
DyedHeatedNatural
Industry-standard treatment
Most commercial black onyx is dyed chalcedony; banded natural onyx is also available
Mineral chemistry
Chalcedony (cryptocrystalline quartz) with parallel banding
Crystal system
Trigonal
Stone family
Chalcedony
Common cuts
RoundFaceted RoundRondelle
Common sizes
4mm6mm8mm10mm
Care notes
Durable (Mohs 6.5–7). Mild soap and soft cloth; dyed material can fade with prolonged sun exposure.
Related stones
Sardonyx, Agate, Carnelian, Chalcedony
Frequently asked questions
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Is black onyx dyed?
Yes — essentially all commercial black onyx is dyed and heat-treated. The process is over a century old and well-documented: chalcedony rough is soaked in a sugar solution, then sulfuric acid, then heated. The acid converts the sugar to carbon inside the stone's microcrystalline structure, producing the deep permanent black that defines the variety. This is what "black onyx" means in the modern trade — the treatment is not an alteration of the stone; it is what makes the stone what designers know as black onyx. Natural pure-black chalcedony exists but is rare and not what the bead trade carries at scale. -
Will the color fade?
No — the dye-and-heat treatment produces carbon that is integrated into the chalcedony's microcrystalline structure, not a surface coating. It does not fade with light exposure, does not leach with ordinary cleaning, and does not require special storage. Black onyx is one of the most color-stable treated stones in the bead market for exactly this reason: the treatment chemistry produces a permanent change in the stone, not a temporary surface effect. -
What's the difference between black onyx and obsidian?
They are different stones entirely. Black onyx is dyed-and-heated chalcedony — microcrystalline quartz, Mohs 6.5–7. Obsidian is volcanic glass — amorphous (non-crystalline), Mohs 5–5.5, formed when lava cools too quickly to crystallize. Visually they can look similar (both deep glossy black), but obsidian often shows conchoidal fracture surfaces and slight translucence at the edges; onyx is uniformly opaque. Onyx is harder and more scratch-resistant; obsidian has a glass-like fracture pattern that affects bead drilling and durability differently. -
What's the difference between black onyx and black agate?
In the modern bead trade, very little — both names typically refer to the same dyed-and-heated chalcedony. Older lapidary literature distinguished "onyx" as banded black-and-white chalcedony with parallel layers and "agate" as banded chalcedony with curved or concentric layers, but in commercial practice "black onyx" and "black agate" have become interchangeable for solid-black material. The buying decision should focus on size, cut, finish (glossy or matte), and supplier disclosure of treatment. -
What sizes and finishes does Dakota carry?
Our active black onyx inventory centers on 6mm and 8mm rounds, with 4mm, 10mm, and 12mm rounds also stocked alongside select rondelles and faceted cuts. Both glossy (high-polish) and matte finishes are represented across sizes. Full size, cut, and finish availability is filterable in the grid above; the spec details for each strand — including treatment, origin, and bead count — appear.