This is an illustration of Ship of Magic, by Robin Hobb.
◊Spoiler warning◊ for those who haven't read so far.
One of the treasures found on Treasure Beach by Kennit (actually Gankis) at the very beginning of the Liveship Traders trilogy.
The description is on page 9 of the UK paperback edition, in the first chapter (called "Of Priests and Pirates").
Photoshop, 12-ish hours.
Yes, the hand is based on a photo of my hand (but it's not the photo, it's redrawn).