Curious about gem box production logic, and your experience with frequency

What exactly is the logic for when someone gets a gem box? I ask because there appears to be a wide range of how often people get them.

I myself have received about 14. A guy I know in my clan has received over 60 of them. Someone else has received about 30. Obviously I am a bit jealous of the people who get it more.

Does anyone know what the logic is behind them? It has to be more than just random because over time a random generator would have provided a somewhat better balance I would think.

How many have you received?