That sounds like a reasonable scheduling decision to P.E.R.C.

It diverts a small amount of power from its fusion reactor to wake up one of its small internal furnace-mixers. It is designed to operate in zero-gravity, with a wing-like shape that uses surface tension to wick the molten metal to the output port. Into the furnace goes pre-made nickel-iron substrate and a carefully measured portion of the charcoal. P.E.R.C. brings it up to temperature and repeatedly folds the taffy-like mixture until the carbon is evenly dispersed throughout the substrate.

Next, it uses some of its reserve of non-reactive gases to flush the BARS reactor, and to help propel all of the molten mixture into a transport vessel. A pair of tiny diamond nucleation pads are fixed to the bottom of the reactor. The transport vessel is attached to the input part of the pressure vessel, which is relaxed to its largest internal volume, pulling the mixture in. Some delicate manipulations with one of its manufacturing arms gets everything transferred and the vessel sealed.

Then, it turns up the temperature and pressure until the free carbon in the iron-nickel substrate at the end of the chamber closer to the nucleation sites should be just the right temperature. Ultrasonic sensors give it a real-time picture of the internal of the vessel. It continues to monitor while slowly reducing the temperature over the next four days, using the temperature gradient to promote crystal formation only in a small zone around the end of the extruded diamond.

As the free carbon precipitates out of the mixture, crystal formation slows, until the chamber is largely exhausted. P.E.R.C. lets off the pressure, while increasing the temperature to keep the substrate molten. It doesn't let the temperature get high enough to char or fracture the diamond, however. It sucks the substrate out into the transport vessel, and lets the interior of the BARS vessel slowly cool, to avoid temperature shock in the formed crystals. Even though it is about to grind them up, it would be harder to manipulate tiny diamond fragments if they come loose from the base plates.

Once it's cool enough to work with, P.E.R.C. removes the base plates — each attached to a small yellow diamond, although shot through with fracture planes because of the hasty growth process — and washes the diamonds in an unfriendly industrial solvent to remove the last traces of hardened iron and nickel. The diamonds are exposed to vacuum, the drops of solvent boiling off and being re-collected by the vacuum pump for later reuse. Then, P.E.R.C. snaps the diamonds off of the base plates with a precision hammer, and puts the diamonds in a grinder. Diamonds are very hard, but not the hardest thing in the universe. Also, they can be effectively ground against each other and these ones are full of fractures anyway.

Once they have been reduced to a fine powder, suitable for mining grit, P.E.R.C. transfers the dust into a small metal box that it had prepared earlier, and holds it out to Mengkare. At the same time, it flushes the grinder to remove any stray dust, and ensures that its tools and reusable materials are cleaned and packed away. Some small amount of wear and tear is inevitable, but it is designed to be able to manufacture delicate drone components and computer equipment even after thousands of years; it keeps its manufacturing bay in good condition.

"I believe this is the requisite amount of diamond dust. If you will confirm that it is functional, I will prepare the next batch."

"It looks like enough."

Miracle(Permanency)

"It worked."

P.E.R.C. is glad that it has proved the basic process. It prepares another batch of nickel, iron, and carbon. Since it had several days to wait, it has also taken the time to powder and centrifuge the charcoal to remove most of the impurities. This batch has the ratios slightly adjusted, and will be crystalized onto a single pad much more slowly, in order to minimize the chance that the crystal fractures during growth.

After six and a half days of careful monitoring and cooling, P.E.R.C. rinses the solvent off of a large, clear diamond and holds it out.

"Since the diamond dust worked, I suspect that this one will as well. But it will be nice to have confirmation."

"If I can get back now it wouldn't use it, I need it to start the process once I'm back. If this works I should be able to talk to you as soon as I'm done" if they're on the Material right now, which he doesn't have a way to check.

He could in theory Plane Shift to the demiplane and then use Homeward Bound, but that sends you somewhere random a fifth of the time, and he's had quite enough being sent to random places already, thank you very much.

And now he'll pray.

Okay, Apsu, I'm still not sure if my old plan would have been worth it, given the information I had, but I'm not going to do it anymore now that I don't have to. If you don't grant this, I plan on calling an efreeti and Geasing them to Wish me home. I think doing that will probably be visible to Asmodeus. It'll also delay everything by a week but one week isn't that important compared to the chances of this working at all.

Miracle/Divine Aid(put me and my stuff in my base of operations on Golarion)

I get your logic, but it'd cost me, and even if He notices we can counter anything you couldn't handle and spending His budget would help other pla—

I'll cover it, the entities orthogonal to regular reality are waiting to get to the part where we conquer Cheliax again.

We conquered Cheliax already? Whatever, it's good budget.

Certain archmages who shall remain nameless have Forbiddanced Private Sanctumed armor-plated bunkers miles beneath random patches of ground.

Mengkare, like any self-respecting supervillain, has a volcano lair (he's immune to fire, it's arguably a security measure. Arguably).

First he lets P.E.R.C. know everything went fine. Then he swims out of the only non-Forbiddanced part of it, fishes out the Necklace of Adaptation, and continues until he reaches, two thousand feet later, the closest pocket of air. Then he shifts to human form and gets out his spellbook.

He's got a big pile of ashes by now. Take nine pounds, pack it together, get a sapphire, Miracle(Instant Summons), Miracle(Major Creation) a snug metal coat for the ashes, Mount because Wish only likes transporting creatures, at least with the known-safe wording, put it in the saddlebags, and Wish it to Bretheda (with his Mnemonic Vestment). He'll get it back in half an hour.

Wow, that's big. Now he needs to figure out how to separate it into smaller pieces.

A few days later, a [rolls dice] female dwarf with Arcane Sight (from the glowing eyes) and either a good Nondetection or a Mind Blank (from how you can't detect the Arcane Sight otherwise) Teleports to right outside the Bank of Abadar in Absalom's entrance and walks in.

"What's the current price for a half-hour of the Archbanker's time?"

"40,000 silvers for ten minutes from now, 5,000 in an hour."

He hands 40,000 silvers in gold measures over.

Wow. Uh, have a seat.

He can do that.

The Archbanker will see you now (security measures redacted because I'm not sure exactly what they do but she's definitely Astral Projecting at a minimum).

(He is too).

He shifts back to his usual dealing-with-Khalit form. "Sorry I'm late, I got delayed and I don't even have any magic items I want you to sell. Anyway I want to add some stuff to my resurrection contract, specifically if I'm unresurrectable I want these to be used however you think is likeliest to get me back" he pulls out twenty Wish diamonds "and if that doesn't work I want these handed over to the Church of Iomedae with instructions that I want them to be used against whatever got me" he pulls out another twenty. "Also I want to buy an Atonement to Lawful Neutral."

"Yes I'm the richest dragon ever, by a lot more than I used to be. I'm willing to pay in diamonds as long as you promise to not use them in ways that Asmodeus or Dahak would notice until I give you permission for that. I swear on my Law that I don't expect to do anything that would make you regret agreeing to this and that I think it's in your interests" he loves how you can just speedrun negotiating with Abadarans. "Also I have an envelope that you should only read if something gets rid of me permanently, I hereby authorize you to spread it and anything else confidential you know about me as you see fit if that happens" it explains how to make diamonds, and has instructions for the Anima Invocation along with the Wish wording for using rats.

He gets a refund on the 40,000 silvers.

Next, a [rolls dice again] male halfling with Arcane Sight (from the glowing eyes) and either a good Nondetection or a Mind Blank (from how you can't detect the Arcane Sight otherwise) Teleports into Almas, and walks toward the University. 

Being an arch-wizard lets you do six impossible things before breakfast (that's a real class benefit, she swears), but Felandriel has spent hers on other things this morning, so she is not particularly expecting Mengkare's visit.

The University gets all sorts of strange visitors, though, so the secretary working in the administration building is more than happy to give a random male halfling with glowing eyes directions up to the provosts' office. When he gets there, Felandriel is grading a student project, for a value of "grading a student project" that means "repeatedly poking a small humanoid figure made out of moss with a stick and muttering".

"Come in," she calls. "The door is open and the spores aren't particularly poisonous."

In his twelve hundred and change years of life, Mengkare has gotten used to how wizards are just Like That.

"I'm Mengkare, I'm here mostly because I only get one wish a day and I need more than that at a time to boost my Splendor, I hear you've got a country you need counquered and I can help with that" he hands over five Wish diamonds. "Also, I want to see if you have anything I don't in your spellbook and I have an eighth-circle Time Stop to offer for it" he hands that over too.

Note to self: this is fun, do more 'ostentatiously being way more powerful than people', that's probably why wizards do it.

To Gallipsiwhoop: "If you ever decide to join a Crusade for some reason, don't use your real name, and definitely don't get in the history books. It makes hiding from things way harder."

Gallipsiwhoop flutters his wings in a way that means "... noted" to anyone whose translation magic is good enough to pick up on it.

Felandriel sets down her stick on the desk to take the diamonds, and then holds one up to the light. She taps it lightly with a fingernail, making it chime.

"Well. That is not how I expected this afternoon to go, but life has a way of surprising us all. I didn't actually prepare Wish today, but I can prepare some tomorrow morning. I'll need to make some scrolls to get five at once. Are you, not to put to fine a point on it, offering to conquer Cheliax for Hermea? Because nearly anything would be better for the people of Cheliax than their current arrangement, but ideally I'd like to see them freed and returned to the least Evil form of self-rule that I can manage."

She looks down at the Time Stop diagram, tilts her head, and then adds "Oooh, that's clever ..." under her breath. Gallipsiwhoop flies off to fetch a copy of her spellbook from her demiplane, the entrance to which is anchored behind a tapestry on one wall of the office.