How to recreate texture envMap functionallty in scene

For weeks now I’m trying to load a ring model inside three js and finally had some decent results using an obj export of the model and the three.js online editor

Tried publishing the scene from the editor and loading the scene as json however the loading time is really bad due to duplicate materials. So I’m now trying to load the model and the textures without using the editor and got to some results but I cannot seem to find a way to recreate the envMap texture functionality. (diamond texture)

I’ve already tried .background = as well as .envMap = , but I believe I need to do something else.

Does anyone have more knowledge on the subject?