The crystal paused its growth. Iron ions—the colouring agent of amethyst—settled on the surface. Then growth resumed, sealing a violet phantom inside.

The phantom is a record of interruption and restart. The purple layer is the trace of iron ions deposited during the pause, coloured by natural radiation. Within a single crystal, two formation processes—amethyst and quartz—overlap.

Crystals with a distinct purple phantom are uncommon. Growth must pause at the right moment, and iron must be available at the right time. The coincidence of conditions is rarer than the stone.