Rift raid boss

I have heard that you can level soul crystals on the raid boss in the dimensional rift. The rumor goes that the 60+ boss will get you from stage 10 to stage 11, the 70+ boss is for 11 --> 12, and the 80+ boss for 12 --> 13.

Can anyone verify this?

My clan always hunts in the 70+ rift, and we never get our stage 10 soul crystals raised. We are all to high a level to hunt the 60+ boss.

You can only go from 12 to 13 in the Hero Rift. Nothing else

Edit: And it doesnt work every time either