Obsidian Fu Character Gourd Bracelet

Obsidian is volcanic glass, not crystal. Its composition is close to glass, its fracture conchoidal, and the edge thin enough to cut. Raw obsidian usually comes in blocks, and after breaking it open you pick a piece without fissures — material full of cracks is liable to blow apart on the lathe. Most of it is solid black; some shows a rainbow sheen in light, or a ring of golden brown, from bubbles and inclusions lined up inside. Hold a piece to the light and turn it: the sheen should move with the angle instead of sitting still.

The gourd is the star of this strand: one gourd bead with a fu character carved on it, flanked by round beads. The waist is narrow, so the drill can only follow the centre line; off a little and the gourd hangs crooked. The fu sits on the belly, dark left in the recesses with the highs polished, the cut shallow enough to feel flat under a finger. A gourd bead wastes more material than a round one: it needs a thick blank, and more is turned away than kept. The blank has to be trued before the tool goes in; a hair off and the bead is scrap, which is why a gourd bead starts from a bigger blank than a round one of the same diameter.

Three sizes, 18, 20 and 22 cm, measured as the circumference of the loop. Measure the narrowest part of the wrist, snug, then add a finger's width — that is your number. Prefer it loose and go up a size; prefer it close and go down; both ways have their adherents. The fit depends on the cord, and elastic cord slackens with wear. When it does, restring rather than toughing it out; a slack strand slides, and the gourd bead turns to the side.

Obsidian feels cold against the wrist, pleasant in summer and a small shock in winter. Its hardness is about that of glass, and a drop on tile chips it — the chip is curved and cannot be repaired. Watch for desk corners and door handles, the two worst offenders. It doesn't stick to a sweaty wrist, which is more than wood can say. Coming indoors from the cold, a film of condensation forms; dry it before wearing. The chill goes off in a minute or two.

Obsidian doesn't mind water, so there's no need to take it off to wash your hands, but keep it out of hot springs — a sharp change in temperature can craze some material. Dust collects in the recesses of the fu, and a dry soft toothbrush lifts it in two strokes. Bag it when it's off, and don't let it share a box with metal bracelets, whose edges leave white scratches on stone. Obsidian doesn't need the cleansing routines people talk about: rinse it, dry it, and let the rest go.