Blue chalcedony is a soft, misty blue form of microcrystalline quartz. Its gentle colour comes from the way light scatters through countless tiny crystals, sometimes helped along by mineral traces. The best-known material comes from Namibia, often sold as African blue, along with lovely stones from Turkey and the USA. It has a glow that seems to come from within, which jewellers call a translucent or almost cloudy look. The Romans prized chalcedony for seals and carved cameos.
At 6.5 to 7 on the Mohs scale with good toughness, blue chalcedony is an easy stone to live with. It works well in rings, pendants and earrings, and it is nearly always cut as smooth cabochons or beads to make the most of that dreamy glow.
Clean it with warm, soapy water and it will happily handle everyday wear.
Some material on the market is dyed to deepen the blue, which should always be disclosed. Natural stones tend to have a softer, greyer blue.
Blue lace agate is its banded sibling, and larimar has a similar soft ocean blue.
