This is Snowflake #25 in the book of 100 Snowflakes. Instructions on Page 56. Pictured on page 27 in Showcase.

“Like an ice prism, this design is characterized by its simple and well-defined shape.”

Finished diameter: 2 5/8 in. (67 mm)
Thread required: 8 yd. (7.3 m)

All pattern samples in this book are made with size 10 thread and a size 5 (1.9 mm) crochet hook.