In the most recent update, Supercell made a change to remove all RNG from gem spawns. It's actually pretty easy to memorize the order of spawns and is a huge help in removing GG resets in colt%.

Here is a video that makes memorizing spawns really easy. If you don’t want to watch that, I’ve wrote it out as well.

The gems will always have the same spawn positions, at least in your first four games. You are able to get the first six gems by alternating between the top middle and the bottom middle of the gem mine, starting with the bottom. The way I like to think about it is if the number of gems spawned is odd, go to the top of the mine. If it's even, go to the bottom of the mine.

The last four spawns are a little harder to remember, but it's not bad. The 7th will be bottom left, the 8th will be opposite that, the 9th will be bottom right and the 10th spawn will be opposite that. Typically then you will be able to run back for the countdown or easily pick up the 11th if you only have 8-9 gems.