Folio from Berroco is an incredibly soft DK weight yarn comprised of 65% superfine alpaca and 35% rayon. The alpaca lends warmth while the rayon imparts subtle sheen and texture similar to silk.
I only give this four stars, out of five, because the twist energy is a bit on the light side and it's somewhat splitty to knit. Also, the yarn shedded like crazy on me - as I was knitting, I'd end up with a lapful of long fibers. But as long as you pay attention, it is a lovely soft yarn, and I'm happily buying more for another project.