Heres a Super Diablo with bullsnake. Look at the color of this bullsnake, this is over black glass!
Usually fairly transparent, you can keep the original color pretty close by using tanned skins instead of dried against popular belief.
You can either use a quality dry tanned skin, or even use glycerin tanned by "carefully"cleaning and degreasing the skin. This was a glycerin base ,oily, soft tanned skin, but after proper prep...here it is! With all its bright yellowish tail color even over black glass.