I started yesterday with over 150 gems (can't remember the exact amount but I know it was over that). It seems that during the day, one of my family may have hit one of those pop ups for instantly getting all your items for some huge amount of gems.
Is this an instance where TL might give them back? We don't buy gems and have spent a LONG time building up our gems, so we are a little disappointed that we used them accidentally.
I think that the pop up was mistaken for one of the ones that pop up when logging into game, and someone just hit the top of the box and voila.... Now down to 29 gems!