This is the Moonstone DK Scarf (4101). Look closely at the lower picture and you will be able to see the additional dimension created by threading the stitches from the far layer through to the near layer to create the colour changes. This is further accented by the difference in the luster of the two yarns. Noro with silk and Blue Face Leicester.
Check the link above to see how easy threading (or quilting) is. I also use this technique to create channels for elastic or ribbon as in the Pinstripe DK Mitten.