When Ulamog, the Ceaseless Hunger attacks he converts the opponents Color Gems to Void Gems but this effects not Energized Gems.
I think this is a bug. I can confirm this with screenshots before and after the attack.
no, energized gems cannot be converted to any other sort of gem, this includes greens ramp spells, colour changing supports and ingest
Thanks for the answer THEMAGICkMAN.
Please close this ticket!
Locking // Alve