Not necessarily *successfully craft*.
You get a fairly large amount of inspiration from just finishing with a few epic or blue "pieces" on a completely failed craft.
For example if you got two epic pieces, it's better for your inspiration to go get that 3rd than to reroll them in hope of getting a blue.
I wrote those values down some time ago. Those are the p2p - values, so there might be some differences, but I don't think so.
10 - 2 epic
20 - 1 epic, 3 blue
20 - 1 epic, 4 blue
30 - 5 green
30 - 2 epic, 3 blue
30 - 3 epic, 1 blue
30 - 3 epic
40 - 1 epic, 4 blue
40 - 3 epic, 2 blue
40 - 5 blue
100 - 4 epic
100 - 4 epic, 1 blue
100 - 5 epic (without inspiration completion)
These are the base values. You can increase them with those things from cash shop or the potion you can craft with alchemy. (However this potion isn't worth it...)
The max value is 400. Therefore you can convert 200 points into 1 illumination point.
maybe it helps