For all users of Sphere 1.4, here is the design for calibre. If you use it, you notice that the icons are not in Sphere 1.4 style, cause calibre is using seperate icons. Here is the folder of calibre images, so that you will get the icon style for Sphere 1.4. Sphere 1.4 is not a must have, this Set also works with other icon themes.

The Sphere 1.4 icon Theme is placed here in deviant art, just take a look in my gallery!

Installation:
1. Extract the archive.
2. In normal way calibre is placed in opt/calibre. Check it first. Otherwise look for the right folder.
3. Become root (Maybe Alt&F2, then type "gksu nautilus", type your password)
4. Rename the folder opt/calibre/resources/images in ../images-old for example.
5. Copy the folder images from the Sphere design to opt(calibre/resources/
6. Enjoy...

All users of the Sphere 1.4 icon theme: This Set will be part of the next update!