The 10 diamonds required for the pressure forge seems exceedingly high especially because you need 10 and they only have a 0.5% change of being produced, the percentage is increased slightly with legendary tier 2 rigor modules however I am still at over 4 hours trying to get a second diamond.

What's your rate of emulsion consumption?

The recipes are a hint about 2 of the things you'll want for a high-pressure science pack build: rigor modules (which you've already got) and a much higher rate of emulsion processing.

I had 8 refineries each affected by 3 beacons with 2 legendary tier 3 speed modules in, there is faster methods of getting the diamonds but it's locked behind the initial 10 (11 technically for the diamond refinement), each refinery also had more than needed of the materials for the emulsion recipe, is there another thing to increase the speed/probability of getting the diamonds that I missed?

Were the outputs full? If they were running continuously at that level, you should have hundreds by now. Either they weren't actually producing because the outputs were full, or there's a bug. Could you take a screenshot of the production stats?