The code for gem fields already exists, we just don't use it at the moment. It's just the same script as ore fields use, but you set the oreValue to be higher in the script parameters. The AR miner AI already knows how to locate ore fields independenly, however it currenty prioritises the closest field rather than the most valuable.., the idea was either have a small gem field close to the base for an initial cash boost, with an ore field for the rest of the game further out ,or leave a gem field further out for players to mine.
Eh? I could do that in 5 minutes flat... I had actually thought about putting it in at one point, but decided against it for the time being... ideally would require some kind of animated 'gem field' model, which would probably have to be hand made per-map, which shows how many gems are left in the field.
<- my paradrop demo video if anyone missed it first time around