Demimateria help.

[Koroem]

I need to whip out about 50 fieldcraft I materia for some crafts I'm gonna be working on. My main desynth is Goldsmithing 77.99. I did a little over 100 silver rings of crafting the other night and was pretty unimpressed with my yield of 8.

Does anyone recall what ilvl that demimateria starts dropping in pairs? I didn't see a single drop pair from the rings I did but distinctly remember getting them as I was leveling desynth.

Are there any other tips that could help produce the amount of demimateria I need reasonably? Does higher ilvl = higher yields or success chance for demimateria?

Adding my follow up post to the original post:

I gathered up mats enough to make 100 thousand needles (level 43 and ilvl 43). I've converted 40 so far and have gotten 13 demimateria. Either lucky, or the yield is much improved as a result of randomly getting either one or two demis now. I'll post my final tally when done. Thanks for the suggestions.

EDIT 21 for 80 now.
31 for 120.
42 for 160.
49 for 170.

I started with exact mats for 100 crafts and via the return materials was able to get an extra 70 crafts with (as noted above) the final yield being 49 field craft I demi materia. Much happier with this outcome. Hope it wasn't just luck. Unless something is proven to be better, I'm gonna stick with thousand needles for my field craft I's. Both time and resources seem to be light for the return.