Original images can be taken from demo content folder, pins and other png folder
You edit them with a vector editor program, like Fireworks and add the colors you wish.
In the theme, the images are in css/css-images folder
Create the same folder in child theme
Add the images in child theme folder
And change CSS in child theme to new image path
Ex for compare icon: (if you use demo pack child theme), after you create the images folder, you add your new images in there and in style.css you change the img path for compare class to your child theme path.
This I had to test, but since it was an easy change I could easily confirm solution.