It's done with two variegated wools (red/pink and black/grey) worked together in a tweeded stitch. Not too tricky once I got the hang of which stitches to slip on which row. The same cannot be said for the combination of navy/blue and black/grey which I'm currently knitting up for myself, as I can't tell the two colours apart under electric light!
And here are some little Swarowski crystal heart pendants, which as you can see were so much fun that I couldn't stop at just one, so one each for the girls, one for me and one that didn't work out quite so well because the black beading thread showed through the crystals
Hard to get the colours of these to photograph well but we have (clockwise from top right) Metallic Silver, Turquoise AB, Rose Alabaster, and Lavender ABx2