Helo how do you draw/paint/render translucency? Like marbles or glass especially, which have refraction and reflection, internally. Geometrically speaking it ll create complex shading given it bouncing lights around.

I practice basic shapes regularly but when it has sculpted forms/things i dont practice because the stuff i dont hav and such, the lighting confuses me and unless i get some tutorial or
Geometric understanding i just know that my stuff is always wrong.

Thus, Any tutorials, diagram/figure or such? Basically it s about rendering glass(es) and such, very correctly.