Black onyx and obsidian are different materials, even when two polished beads look much alike. Onyx belongs to the chalcedony family of fine-grained quartz. Obsidian is natural volcanic glass. Start with those names before deciding which black surface you prefer.
Ask what the onyx label describes
In jewelry, black onyx is often a name for black chalcedony. GIA’s research on black opaque gems describes treated black chalcedony under this trade name and documents other materials that have been sold as onyx. A short color label therefore leaves two useful questions: what is the material, and what is known about its treatment?
If chalcedony has been dyed black, the material and the added color should be described together. Ask for plain wording rather than trying to infer treatment from a perfectly even black. A photograph is a view of the finished surface, not a treatment report.
Understand what glass means for obsidian
The US Geological Survey describes obsidian as volcanic glass formed when lava cools too quickly for substantial crystal growth. The word glass here describes its structure and formation; it does not mean the material was made in a factory.
That still leaves an item-specific identification question. Manufactured glass and several other dark gem materials can resemble a polished black bead. GIA’s black-gem study explains why professional examination may require several kinds of evidence. One glossy reflection or a glow at an edge cannot establish the whole identity.
Compare the finish you will actually see
Look at a full piece and a close view under ordinary light. Notice whether the highlight is sharp or soft, how the bead edges are finished and whether the black line is interrupted by metal. Ask for another angle when a bright reflection hides the surface. These observations help describe the look you want.
JAMBHALA’s BO bracelet is listed as black obsidian with a focal bead in matte 18K gold-plated brass and an elastic core. Its polished black beads and quieter metal surface create a contrast within one bracelet. Compare the whole strand beside a sleeve as well as in close-up to see how much of that contrast remains visible.
Read the construction before choosing
Check bracelet size, visible cord, fittings and the care instructions for the complete piece. Keep beads from repeatedly knocking against harder jewelry and set a chipped or damaged piece aside for assessment. Avoid scratch tests on finished jewelry you want to keep unmarked.
Before ordering, save the material description, any treatment disclosure and the size you selected. Those details give you something concrete to compare with the delivered bracelet, alongside the finish that first caught your eye.
