rule

Should have been emeralds

The cost of a recharge should never be divisible by the number of gems you can buy in a pack. That way you always have some amount left over and will need to buy more in order to use them up completely and "get your money's worth".

Seems legit.

Reminds me of the internet king episode of the Simpsons

Ah, my first repost on Lemmy. What a time to be alive.