Emperor's Jewel question

[Philbatrax]

So the Emperor's Jewel has a 50% chance of granting a free artifact use.
Can you tell ahead of time if that's going to happen, like, does it glow differently?
If you can tell, then I might actually use it instead of artifact hoarding.

[cz]

Bumping this because I have the same question and apparently no one on the internet has ever answered this before, which is very weird to me.

As far as I can tell, it's a pure 50/50 chance *rolled at the point when I hit R1 to use the artefact* whether the use is free or not, and there's no chance to tell ahead of time. There seems to be no difference in the shield's gem's glow if its ability is "active" or "inactive". Unless there's some subtle visual cue my tired eyes are missing?