This lovely flake was originally shared by Emma Crew back in 2001 on the now-defunct geocities, but is fortuitously still available via the wayback machine. (If anyone knows of a current website for Emma, please let me know!)
In the original pattern, each petal contains a butterfly (the "flutters") tatted separately in size 80 thread. I skipped the flutters partly because I really like the way it looks without them; the petals have an unusual onion-dome look to them. The other reason is that it's almost impossible to match whites across dye lots, much less two different sizes and two different brands, and I wanted an all-white snowflake.
I didn't do a great job blocking this one, but also I found it a little tricky to get the junction where the chains reverse direction to lie neatly - I tend to pull too tightly on the first stitch and pull them out of alignment, as you'll notice if you look closely. People with gentler tension will find it goes more smoothly; if you include the flutters the join happens at the transition so it is less obvious even if your tension is too tight. It's possible to skip the transition and have a simple curve for the chains, but I think it's not quite as attractive.
Pattern available here thanks to the internet archive/wayback machine.