I had to take several runs at this one before I got to what you see. My first center ring cupped dramatically. Tried again, lengthening the chains to 6-6: then the chains of the outer round were not long enough, and I ended up with something that might drape over an ornament. Undeterred, because I love the shape of this snowflake, I started over.
In this version, the rings of the first round are R 5+3-3-5, linked by Ch 4-4 (still cups a little); and the linking chains of the second round have been changed to 4-4.