I started this painting for the Open Figure Drawing Workshop but didn't manage to finish it for the deadline. The original is a painting by Ingres, called "Princesse Albert de Broglie, née Joséphine-Eléonore-Marie-Pauline de Galard de Brassac de Béarn" (phew!).
I used the grid method to help me with the drawing and it was all painted with a Wacom graphire in Photoshop. I'm not exactly sure how long it took me because I worked on it off and on for months. But I can assure you it took many hours!! I did not start the painting in greyscale, but started immediately with color. If anyone is interested in seeing the WIP thread it can be found here:

http://forums.cgsociety.org/showthread.php?f=31&t=460167

Thanks for looking!