Here's the photo that I got:
Well I went back yesterday and the beautiful butterfly was back. After much chasing and stalking, I managed to get a better picture. I looked it up and it's called a Great Purple Hairstreak (Atlides halesus). Here it is in all its glory:
I still wish the focus was a bit sharper, but this guy is really cautious. If I see it again, I'll try laying in wait for it instead of chasing it around the field.