DaveYKMore wrote:

So my question is, besides Strange Peaches which very rarely offer Delicate Diamond, Where can I find Diamonds?.

Idk if this can help you. Or maybe you already know it.. .but anyways if you have superior alchemy.. I never try using junior alchemy.
Go bangkok and theres and NPC there buy
Gem necklace + grape syrup or(any rank 8 material.) compound it..

Thats the fastest way to get diamond for my opinion..