When the 3x gems reward was up, i managed to hit a good bonus on a run thru harvestshield, which brought me from mid 300s in gems to over 700.
But when i logged in just now, i am back down at 300ish gems, without me having knowingly used any.
Not sure how to check on it, though, as i don’t have any screen shots of the dice roll post event, or having that many gems.