Since they made nether vortices BoE, and my mage had some left over from my old guild, i made my alt rogue a Belt of Deep Shadow (BoE epic leather belt). He had run Magister's terrace once and got the epic bop gem so i decided to put it in the belt. However, when i put it in the belt i realized the belt was still boe even though the gem i put in it was bop. This could be useful if say you wanted 2 12 spell dmg gems for your mage in an item like Belt of Blasting and you have an alt that is capable of running Magister's. All you have to do is make the belt, give it to your alt, and have him take the gem that has 12 spell dmg and put it in the belt. Then send it back to your mage, and put the one your mage got from Magister's in the belt and wellah, 2 12 spell dmg gems.
Also, it may work for the BoP epic j/c ones as well but i doubt it.