It looks like you could cover the cake in fondant and use a straight edge to make the impressions that give it that look. Almost like you would do a quilted look on a fondant cake. I could be wrong, though, since I have never done it before. It's a beautiful design! So elegant. Good luck and post your pics!
Good ideas in the thread enga posted. I would also consider decorating this cake upside down, just so that top edge is perfectly flush. Bottom edge can be covered with that ribbon and pearls so it's not so critical to get it as perfect as the top.
Thank you sooooo much for all your replies!!!! They have given me a very good idea on how to tackle this decoration and am actually looking forward to doing it! .