Rough crystals, 500 g — Tiger's eye

Tawny and brown bands crossed by a moving sheen that slides as you tilt the stone — chatoyancy.

The stone as the earth formed it, simply freed from its matrix and cleaned. Sharp edges, irregular faces, a matte or glassy luster depending on the vein.

In tradition. A protective stone renowned in many cultures, tradition credits it with turning back what comes from outside, like a mirror.

Use & upkeep. Set it on a tray, in a bowl, next to a candle. Rough pieces sit well beside polished ones, by contrast. Rinse under clear water and dry; some soft materials cannot take water, check first.

• Its sheen comes from asbestos fibers replaced by silica without their parallel structure being lost.
• A natural piece: shade, veining and dimensions vary from one example to the next

A decorative object for personal practice. It is no substitute for medical advice or treatment.