Under electric light, black goes grey. Midnight goes blacker than black. The old houses knew.
Black cloth under electric light does something disloyal: it goes grey-green, flat, faintly dusty. Midnight blue does the opposite — the deep blue reads to the eye as a richer, denser black than black itself. This is not taste; it is optics, and photographers have known it longer than tailors.
The Duke of Windsor's evening clothes were midnight. So were most of the great houses' — cut in midnight barathea precisely because their clients were seen by candlelight and chandelier, never by daylight. The rule survived because every photograph proved it.
A wedding reception, an award evening, a dinner — every hour a tuxedo works is an artificially lit hour. And in the one setting where the two cloths stand side by side, the man in midnight looks like the photograph and the man in black looks like the print of it.
The house cuts both, and will show you both under the atelier lights before a rupee is spent — the comparison takes ten seconds and usually ends the debate. See it for yourself before an evening commission.
The house will write to you to confirm the hour.