Schizophrenic Dissociation question.

The bottom line says "non-cluster jewels socketed in your passive skill tree has no effect."

A reddit comment made this claim:
"IIRC cluster jewels aren't considered a part of the passive skill tree, so you can still put abyss/cobalt/crimson/viridian/prismatic jewels inside of the sockets provided by the large/medium clusters."

So... is that accurate? Will any jewels work as long as they are part of the large/medium cluster jewel socket? Or no? Thanks in advance for the response.