Converted the pattern from the book to an in the round pattern; main thing is to remember that alternating odd rows need to be offset by one stitch. So that extra knit stitch at the beginning and end of 1, 5, 9, 13, 17 is important; since this is in the round, the first knit stitch can be replaced by a suitable twist stitch (which of course must start one stitch before the new row), and then the last knit stitch can just be a regular knit stitch because it’s really part of the even rows, which are now all knits, not purls.

Pattern:

Cast on 80 stitches
Knit a few k1p1 ribbing rows
Knit the diamond pattern for about 30 rows
go back to k1p1 ribbing for more rows
decrease the ribbing via “slip one, k2tog, slip back and over the tog” so as to preserve the ribbing as high up as possible.

change color as appropriate.

Very thick.