*results not guaranteed. You may still suck.

nuna is a goldsmith! among other things.
How the hell does crafting work, anyway?
I wondered this, too. Actually, everyone did. I witnessed a zone full of people flail madly as they attempted to discern the secrets of even getting past the “Synthesis” menu. Some didn’t even get that far. So here’s the scene: you begin crafting. Oooh, the pretty lights! And oh look, sparks! Whoa, what’s that halo around my glowy blob? Oh my GOD, how exactly does embroidery EXPLODE?
Yeah, we’ve all been there. Here’s how not to be. This is geared toward local leves, since in theory you’ll be doing tons of them to grind your level high enough that you don’t fail low level real synths. For the uninitiated, local leves let you use NPC-ingredients to make items for NPCs. You don’t actually GET the items, so your dreams of stealing some poor woman’s Blacklip Oysters is dashed. You actually have to MAKE her the Bone Hora, and in return you get a healthy stack of carrots.
Well, and essentially free experience.
What’s the difference between the kinds of synthesis?
It’s fairly self-explanatory, but with a few things that aren’t immediately obvious. Standard gives you fair Completion, fair Quality, and on a success, uses little or no Durability up. Rapid gives high Completion, no Quality, and always uses Durability up. Bold gives the lowest amount of Completion, high Quality, and always uses up Durability.
So, what about the colours?
It’s been said that MMO players (or all gamers, really) are a cowardly and superstitious lot. As such, there were tons of theories floating around regarding the magical

nuna and raze make sweet crafts together
crafting colours before SE released anything. Some people said white meant do Standard, yellow meant do Bold, and red meant do Rapid. Others said white meant Standard and yellow meant Bold, and red meant Wait. And while basically no one knew what to make of the changing-colour state, everyone got that the woobly halo and the sparks were bad. SE’s official release says that white means high odds of success (NOT guaranteed. There is ALWAYS an element of chance in crafting), yellow means lower odds of success, and red means low chance of success. However, if you do Bold on red and it succeeds, you get a significant Quality boost. It says nothing about the changing-colour state, so we can just assume that is a sort of wild card.
Okay, I get it. How do I make high Quality items without failing?
It’s not easy, and because there’s always that element of chance, there will be some crummy synths, even if you’ve got fancy cooking armor and a funny hat, and have access to a cookery (400g at your local camp warden!) and are level 99. Here is my personal method for making good stuff well.
Your local leve will give you 2 extra sets of ingredients. USE THESE, EVEN IF YOU DON’T NEED THEM. You don’t get the items from them, but you DO get the XP/SP and it also ups your reward from the NPC (especially if they’re good quality). Let’s say you have to make two Bone Hora for your quest.
For the first two, my strategy is:
1% – 80% Completion: Standard on white, yellow, and wild card. Wait on red.
80+% Completion, if Durability is 40 or higher: Bold, regardless of colour. If it fails, go back to Standard.
80+% Completion, if Durability is lower than 40: Standard on white, yellow, and wild card. Wait on red.
For the second two:
1% – 80% Completion: Bold on white and red. Standard on yellow and wild card.
80+% Completion, if Durability is 40 or higher: Bold, regardless of colour. If it looks bad, switch to Standard.
80+% Completion, if Durability is lower than 40: Standard on white, yellow, and wild card. Bold on red.
Using Bold synthesis on red is a gamble, but with the last two, they’re technically “free” anyway, so I don’t mind the risk. To be honest, it works out for me at least as often as not, if not better.
Bonus Question: What happens if I let the timer run out?
You “Wait.” This loses you 1 Durability the first time, 2 the second time, 3 the third, and so on. So don’t go AFK at the wrong time!
Bonus Question: How much is the most durability I can lose in one go?
I’ve seen it go as high as 25, although it’s usually below 20, depending on colour/synth type. Beware that it can go higher, though! There have been plenty of times that I’ve gambled a synth because I had 20 and it ended up taking away 23.

a post-craft cuddle
Hopefully these guidelines will work out for you as well as they have for me!
If they don’t, please don’t MPK me or refuse to teleport me. If they do, however, feel free to shower me with gil and presents.