Iridescent Silk

Taken all the way down to base materials, one Iridescent Silk is 2 crafting steps deep and needs 1 intermediate — Iridescent Silk Thread ×3 — which resolves to 2 distinct raw materials totalling 5 units, plus 6 crystals.

That bill outweighs 4,201 of the 13,602 recipes tracked here and 464 of the 1,968 Weaver ones, and 4,464 recipes nest deeper.

Only 3 of those crystals go into the final step; the other 3 are burned by the intermediates, so the real crystal cost is 6 Lightning Crystal.

Every step is Weaver work, from a Lv 72 intermediate up to the Lv 72 finish, so one class covers the whole chain.

Both raw materials are gathered, and no spot for either is timed, so nothing in the tree waits on the Eorzean clock.

Iridescent Silk is itself consumed by 36 further recipes, spanning four of the eight crafting classes.