Gemscope

Taken all the way down to base materials, one Gemscope is 3 crafting steps deep and needs 6 intermediates — Mythril Ingot ×4, Brass Ingot ×1, Clear Glass Lens ×1 and 3 others — which resolve to 8 distinct raw materials totalling 24 units, plus 36 crystals.

That bill outweighs 8,926 of the 13,602 recipes tracked here and 1,346 of the 2,216 Goldsmith ones, and 337 recipes nest deeper.

Only 10 of those crystals go into the final step; the other 26 are burned by the intermediates, so the real crystal cost is 21 Fire Shard, 10 Wind Shard and 5 Water Shard.

The chain crosses four disciplines — Goldsmith to Lv 42, Blacksmith to Lv 38, Alchemist to Lv 28 and Carpenter to Lv 25 — so no single class can finish it unaided.

All 8 raw materials are gathered, and not one of their spots is timed, so nothing in the tree waits on the Eorzean clock.

Of the intermediates, Silver Ingot has the widest use: 157 recipes call for it, spanning eight of the eight crafting classes.