This fair-isle hat features an all-over color pattern that is reminiscent of tiny diamonds. The ribbed brim is extra stretchy for a nice, snug fit. And the fair-isle technique creates a fabric that is especially thick and warm. This beanie is finished off with centered double decreases that maintain the diamond colorwork all the way to the very top. Tip: choose a self-striping or multicolored yarn as your main color for an even more visually interesting effect.