So this was really weird. I had 115 gems, and stepped away for a few minutes, when I returned it started showing as -45 gems! I added two from a balloon and it went back to 117. Pic enclosed 
It’s done it a couple more times and consistently is 160 below the current level until you add more when it goes back to the correct total
Thank you for letting us know. This is so weird. May I please grab your id?
Yes, it’s bm4kz3 - I haven’t noticed it today at all.
We are investigating your logs and may find an issue that may lead to this bug. I’ve sent some gems to your account as a token of appreciation (it should add to your total automatically and you may need to restart the game to see the total increases).
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Thanks - and I did say I could break any software!! 
I’m sure I missed my vocation as a bug tester 