Also called: Watch-glass nails · Domed nails · Clubbed nails · Spatulate nails

Where on the hand: On the nail plate, best seen in side profile.

What it looks like: Domed like a watch-glass, curving over the fingertip in both directions, with the fingertip itself often bulbous beneath it.

Traditionally the strongest disease indicator in the whole nail repertoire: weak lungs, bronchial and respiratory trouble, cardiovascular conditions, and lymphatic risk.

Read with care: This is the one nail sign where traditional doctrine and medicine overlap: nail clubbing is a recognised clinical sign. That makes it more important, not less, to say nothing predictive — anyone noticing it should see a doctor, and a palm reader should never offer a diagnosis.