Frequently asked questions

• What is sardonyx, and how is it different from onyx or carnelian?

  Sardonyx is a banded variety of chalcedony — microcrystalline quartz — built from alternating layers of sard (brown-red to orange-brown, the same material as carnelian) and onyx (black or very dark brown). Onyx by itself is the solid black-banded form; carnelian is the solid orange-to-red form; sardonyx is the two stacked in parallel bands. In bead form, the banding direction depends on how the rough is cut, so some strands show pronounced stripes while others read as a single color with subtle layering visible only on close inspection.
• Is sardonyx commonly treated, and what should I expect?

  Sardonyx in the bead trade is typically natural, heated to deepen or stabilize color, or dyed — chalcedony takes dye well, and a lot of material sold as sardonyx or onyx has been color-enhanced to sharpen the contrast between bands. Heat treatment is permanent and stable. Dye is generally stable on chalcedony but can fade with prolonged UV exposure or solvent contact.
• How durable is sardonyx for finished jewelry?

  Sardonyx sits at Mohs 6.5–7, the same range as the rest of the quartz family, which makes it a workhorse for most jewelry applications. It handles bracelets, necklaces, and earrings well, and it's durable enough for rings if the setting protects the bead from direct knocks against hard surfaces. Clean with mild soap, warm water, and a soft cloth. Avoid ultrasonic cleaners, steamers, and prolonged exposure to harsh solvents or chlorinated water — dyed material in particular can shift color under those conditions.
• What designs does sardonyx work best in?

  The banding gives sardonyx a graphic, art-deco quality that pairs well with metalwork — bezel-set focals, sterling or oxidized silver, gold-fill spacers. The brown-red-and-black palette bridges warm and neutral tones, so it works alongside carnelian, smoky quartz, hematite, black onyx, and bronzite without clashing. Smooth rounds and coins read classic and substantive; star cuts and faceted shapes catch light along the band lines and add movement. 6mm and 8mm sizes are the sweet spot for layered necklaces and mixed-bead bracelets; larger focals do well as centerpieces against smaller neutral beads.
• How do I tell sardonyx apart from dyed onyx or banded agate?

  All three are chalcedony, so the mineralogy is identical — the distinction is the banding pattern and color. True sardonyx shows parallel straight bands of sard (brown-red) and onyx (black). Banded agate shows curved, concentric, or irregular bands and often includes white, gray, or translucent layers. Solid black material with no visible banding is sold as onyx, frequently dyed to even out the color. In practice, the trade uses these names loosely, so if banding orientation or color tier matters for your design, confirm cut and treatment before ordering.