Single-crystal sapphire.
A4. Five millimetres.
Colourless grown corundum, nine on the Mohs scale, second only to diamond, the same material trusted in observatory windows. It resists scratching, fading, fire, and the slow erosion of time. It is built to outlast the very languages it is written in.
The front carries the family's chosen words. The back carries the lighthouse mark and the edition number: Nº I, then Nº II, and so on. The front belongs to the family. The back belongs to the record.
