Arvid Schneider showed awesome materials and explained how to make some of them.
Take a look at these marvelous crystals made by Arvid Schneider, Senior Visual Effects Artists at Image Engine, in Houdini and Arnold. The best news is that you can create one yourself with the free tutorials Schneider kindly provided.
Aside from the step-by-step instructions using geometry, VDBs, and shader workflows, you can get the source files from the artist's Patreon.
Here are some other beautiful crystals from Schneider:
Arvid Schneider has worked on several well-known Hollywood feature films like Jurassic World, Transformers, Spectre, Aquaman, and more.