Hi man. Similar thing happened to me. When buying for the first time it glitched, as you might have noticed the game isnt finished, but lets not focus on the details. When i tried to buy again i got the first gems without any payment. The glitch unglitched lol. So just try rebuying it. If you don't get any gems then contact playmage support again.
What are you trying to buy with the gems? What's your ingame name? I suggest you to buy purple eggs.
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https://m.facebook.com/petar.kaserI can tell you the secret of my success.⬆️
Mark my words, I will be last on the scoreboard one day.