There are two kinds of sparkle. The kind that announces itself from the doorway, and the kind that waits to be noticed by the one person in the room who would know. The posh, without exception, wear the second. A stone need not be large to be devastating; it need only be right, and worn as though it were the least interesting thing about you.

The same holds for the wrist. A very good watch tells the time, certainly, but its real function is to be spotted by another very good watch across a dinner table and to say, silently, ah, you too. No words are exchanged. None are needed. This is a language older than money and considerably more discreet.

Our guidance is unchanged and unfashionable: buy less, keep it longer, and let it be inherited rather than photographed. The poshest jewel in any room is nearly always the one with a story attached and a grandmother's name on it — worn, faintly scratched, and utterly beyond price.