Lucky cat — Black obsidian

A volcanic glass of absolute black, polished so deeply that it becomes a mirror.

A piece carved from the solid block and then hand-polished; the motif follows the natural veins of the stone, so no two examples fall the same way on the design.

In tradition. Used as a scrying mirror since the Aztecs, tradition credits it with reflecting back what you would rather not see.

The motif. The maneki-neko, the cat with a raised paw, has been inviting prosperity into Japanese shops since the nineteenth century.

In practice. A piece for a cabinet, a desk or a shelf, it stands on its own. Dust with a dry cloth; avoid water on pieces with soft veining.

• It is not a crystal but lava cooled too fast to crystallize — a natural glass, brittle and sharp.
• 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.