Just to add about transparency, although not very scientific...

The more surface thickness you have in the design of objects the better things like transparency, luminosity and reflectance will take on a real life appearance.

Surface thickness for example in 3D software can be done by subdivision. What this does is add more planes (actually vertices are added.) With more planes, there is more area for rendering to do its job when trying to emulate a transparency.

You can with the patience of a Saint or Devil emulate transparent glass with 2D software.