This is a quick to make hat in single crochet using the Tapestry Crochet technique. 3 sizes are offered, 22, 23, and 24”. You will need approximately 65 g of Main Color and 25 g of a Contrast Color of an aran or worsted weight yarn.

For the blue/lime version with smaller diamonds, follow these mods:

Small Diamonds Version

Use a multiple of 6 for starting Round 19 so adjust your stitches in Round 18 to get to 72, 78, 84, or 90. For this hat I used 90 st with worsted weight and an H hook for an XL size. Follow the same method for diamonds starting with 5 in MC, 1 in CC, followed by 3 and 3, 1 and 5, a solid round of CC, and so on. Follow photo for guidance.

With all sizes, you can snug up the last round a little bit by skipping stitches on the last slip stitch round.

Pattern support at my Ravelry group.