Hooray, a new (free) pattern! I made Naiya with a single skein of super-soft bulky alpaca weight yarn that I bought in Cuzco and which doesn't appear to be available anywhere else; I think any bulky alpaca yarn (or a similarly drapey fiber) should work just as well. The minute we left Cusco, I found myself wishing I'd bought enough of the yarn to make something much bigger, so my goal with this cowl was to squeeze as much as possible out of a small amount of yarn, so that I could at least pretend I was wearing something big and opulent. Because the yarn is so floppy (especially when blocked!), you can make the circle relatively small and still have something that doesn't look too tight - it took a few frogged false starts, but I'm very happy with the way it scrunches around my neck.
If you're interested in making this cowl yourself, I think any bulky weight yarn with a good drape should work nicely. If your yarn is a bit stiffer, it might be worth knitting a slightly shorter cowl, and if your gauge is a bit off, you can always easily add or subtract 4 stitches from the stitch count to adjust.