gemstone

Blue chalcedony bead necklace

Chalcedony, microcrystalline quartz (SiO₂), commonly blue-dyed or blue-gray natural chalcedony

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent blue to lavender-blue, waxy to vitreous luster, cryptocrystalline quartz with no visible cleavage; specific gravity about 2.58–2.64. Faceted/tumbled beads and uniform color suggest possible dyeing or enhancement.

Identified September 18, 2026More gemstone →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, often in volcanic rocks, through low-temperature deposition; specimens range from ancient to modern geologic ages. Common sources include Brazil, India, Madagascar, Namibia, Turkey, and the United States.

Uses & applications

Used for beads, cabochons, carvings, ornamental objects, and inexpensive jewelry; the pictured item is a finished necklace with metal fittings.

Geological facts

Blue chalcedony is valued for its soft color and translucency; natural vivid blue material is relatively uncommon, while dyed agate or chalcedony is widespread.

Field identification & locations

Identify by its smooth waxy luster, hardness, conchoidal fracture, and lack of cleavage; glass imitations may show bubbles or lower hardness. A loupe and acetone swab can sometimes reveal dye concentration, though testing should be cautious.