Chalcedony [kal’ sedni] is the microcrystalline to cryptocrystalline standard form of silicon dioxide (SiO₂), which occurs in several different colors and forms, including diamond, agate and jasper.

The reference to microcrystalline or cryptocrystalline is due to chalcedony’s makeup of crystals so small that they are only microscopically visible. The stone has a vitreous to waxy luster, which lends itself to a high-grade polish.

Some of the most sought after colors for chalcedony are the hues of red, pink, orange, blue, lavender, purple, banded and multicolored material. The stone is a source of different semiprecious and precious gemstones depending on it's coloring, impurities or lack of.

Some of the most sought after varieties of chalcedony are Agate, Aventurine, Bloodstone, Carnelian, Chrysoprase, Jasper, Onyx, Sard, Sardonyx and Tiger’s Eye.