This is the "Large Crystal Snowflake" from Vida Sunderman's book Tatted Snowflakes, though I added picots in the center instead of hanging a crystal there. Mine looks slightly different from hers (see the cover below; it's the lower left snowflake) due to my picot size.
A comment about the book: this is one of my favorite snowflake books as it has a lot of very lovely snowflakes. I'm also grateful it's published by Dover, which means it is both inexpensive and unlikely to go out of print. But there are two downsides: most patterns do not lend themselves well to using split rings/chains to climb between rounds, and the patterns are not diagrammed. I've tended to draw diagrams in the margins of my copy.
(Note: in order to insert the cover image I signed up for Amazon's
affiliate program, and am supposed to include this text: “I'm a
participant in the Amazon Services LLC Associates Program, an affiliate
advertising program designed to provide a means for sites to earn
advertising fees by advertising and linking to amazon.com.” My comments about the book are my own, and I am not promoting one retailer over another.)