I'm pretty sure there's no such thing as a peony essential oil. At least I've never seen it. As for FO's WSP has a Peony that has fairly good reviews but I can't speak first hand. I dislike most florals so only make a handful.
I have a peony FO I (think) it's Crafters Choice from WSP but will have to double check when I get home tonight.
I haven't used it yet because to me it doesn't smell quite right in bottle, but then, I have allergies. A friend says it's spot on to her, so I may make a sample bar tonight to test it. I'll let you know if I do.
I have Peony Petals from Sweet Cakes. I actually just soaped it last week, and so far the scent is there. I'm using up some miscellaneous FOs, so blended it 3:1 with SC Lilac. I've used the peony before in MP and lotions, but this was the first time in CP. I'm not big on most florals, but this one I really like.
I soaped with my Crafters Choice Peony FO last night (better late than never right?). I had a lovely ITP swirl going until I realized I'd actually forgotten to add the FO. So it was added at a medium trace and blended just until it was mixed in. I didn't have any acceleration once it got added, and all in all very nice to work with.
As I mentioned, I had my doubts OOB, there was something a bit chemically and not quite right in my nose, but as of tonight when I unmolded, all my concerns have proven to be for naught. It is much truer to real peony fragrance in the soap, and while it is delicate, it is still very obviously there and quite lovely. I would certainly recommend it.
Now we'll just have to see how well the fragrance stays through the cure.