Originally Posted by Elut

Brilliant Glass is definitely rerolling.

I opened 15 today, all of which I had looked into previously. One had become an epic Sapphire.

Interestly, none of them had Rubies prepatch (I had looted those already) and none of had turned into Rubies. I don't have notes, but the distribution of rare gems seemed similar to what it had been.

If you imagine the likely hypothesis that the loot table just had a few rare entries added to it, but the "roll" was not effected, this may make sense. Since the table is not that different, it leads to the following unverifiable conclusions:

1) (Likely) Most BGlasses would have the same gem they used to.
2) (Likely) The chance some gem of changing to another rare would be similar to the chance of of changing to an epic.
3) (Speculative) Only one type of gem (maybe 2), would have a small chance of going epic. This assumes the epics are all in a group on the new loot table.

If these were true, I was wrong to pre-loot the Rubies (most would have stayed as Rubies), and I was lucky that they were not the only gems that could become epics.

There is also a 4th unverifiable conclusion:

4) (Grossly speculative) The gem that could go epic would probably be the first or last alphabetically - Dawnstone or Talasite. I don't take this one too seriously - there are too many other ways to sort data.

EDIT: Torq's post right before mine supports conclusions 1 & 2, and refutes 4.