Generally speaking your goal is to make the outermost path(s) into one path, offset it and then make that offset path a different color from any other paths.
For this design, I’m thinking that is the starting point of a lot of work hand editing nodes. You probably have a bitmap image of this? (.bmp, .jpg, .png) I’d do a bitmap trace in Inkscape, delete all of the inner paths it is going to create and then work with the outside one. There will still be a bit of work.
Have you considered going to the noun project, searching for crystal, and then placing the artwork inside the crystal icon for your outside cut? It’s been many years since I saw the movie, if there was a book I never read it, so I can’t remember any relevant themes for other ideas.