Michele Carragher, the head embroider on Game of Thrones, made this awesome tutorial to show how she created the dragonscale fabric that appears on several of Daenarys’ costumes in S3 and S4.
Ms. Carragher says that the dragonscale fabric was created because “In season 3 the Costume Designer Michele Clapton wanted a Dragonscale like textured embroidery that starts to emerge on three of Daenery’s costumes, which becomes heavier and more pronounced, growing and evolving as the season progresses” (Carragher).
In stages 9-11 of the tutorial we see how the textile evolves from lightly to heavily embellished. This progression is meant to illustrate Daenarys’ personal growth and the growth of her dragons (source).
Here’s a link to Ms. Carragher’s website.