The jewel of Golbez's possession that Rubicante spoke of could have been just metaphor for a personal philosophy or goal, but it felt too deliberate. I thought it was obvious set up for Golbez having a Crystal of Light from Hydaelyn same as Ardbert and Co and a similar 'Failed WoL' mirror foil, but it could easily be a Dark Crystal like we haven't seen since ARR or a shard of Sabik that he picked up on the Moon. Or perhaps he was the original patsy of Igheyorm, and it's just that variety of auracite.