As of patch 6.2 in FFXIV, tomestones of Astronomy are our level 90 uncapped tomestone, which means they’re used to buy endgame crafting materials and some catch up gear.
You’ll collect Astronomy from level 90 activities like duties, roulettes, hunts, and treasure maps. If you’ve got a stockpile here’s what you can buy with them.
Tomestones of Astronomy can be spent with Cihanti <Tomestone Exchange> at Raz-at-Han [10.8, 10.3].
Astronomy tomestones are very important to crafters because they’re used to purchase max level crafting materials for making equipment strong enough to enter the current tier of savage raids.
There are also materials that are used in the crafting of combat potions called tinctures. These consumables have consistent demand compared to equipment, but typically have more competition on the market.
Even if you’re not a crafter you still shouldn’t let your Astronomy overcap! Buy the materials and sell them on the marketboard for gil. The six expensive materials at the top of the list are the ‘current’ materials. The cheaper ones are from the previous tier and aren’t worth much anymore.
Check your marketboard to see what’s worth selling on your particular server. A quick way to do this is to set up a favorites list. Right click an item in the search results and add it to your favorites list.
Using the favorites button in the bottom left of the marketboard window, you can quickly check your list and see which of the materials is worth the most and spend your tomestones on that one.
Buying Catch-up Gear
You can also use tomestones of Astronomy to buy the Radiant set of equipment. You may recognize this equipment set as the NPC garb of the members of the Radiant Host. You’ll probably have seen them around Thavnair and during the Endwalker MSQ.
At item level 590 this gear is good enough to take into level 90 dungeons and story mode trials and raids. Since Astronomy can be farmed pretty easily, this is a decent option if you’re simply looking to try out a new job in max level content.
If you’re a fan of the glamour and you’d like to dye it you’ll need to upgrade it to item level 600.
The Roborant (for weapons), Twine (for leftside pieces), and Coating (for accessories) can be purchased from Nesvaaz <Tomem and Sundry Exchange> at Radz-at-Han [10.6, 10.0] with tokens from Aglaia (level 90 alliance raid).
These upgrade items can also be obtained with sacks of nuts from the appropriate hunt vendors in Old Sharlayan or Radz-at-Han.
Take the Radiant equipment and the appropriate upgrade item to Khaldeen <Gear Exchange> at Radz-at-Han [10.9, 10.4] to trade them for the Augmented Radiant equipment.
A Note on the Tomestone Cycle
The way currencies work in FFXIV is that at any given point there are two endgame tomestones. Both tomestones can be collected with max level (90) jobs, but one has a weekly cap (450/week) while the other may be farmed indefinitely.
With every even numbered patch comes a new capped tomestone (Causality in 6.2), at which point the previous capped tomestone (Astronomy) becomes uncapped. The previously uncapped tomestone (Aphorism) is phased out and is no longer used to purchase things from vendors.
If you haven’t done so already, you can exchange any unspent tomestones of Aphorism for Astronomy.
Keep in mind that as players obtain more and more gear from time-gated sources like savage raids and Causality tomestones, players will have less need of these crafting materials and potions. Astronomy’s value will go down over time so be sure to make the most of them!