Standing still doesn't determine shit. Standing there for hours, or moving around gives you the same amount of gems. I've mined around 7 gems today, one of my miners were mining for 5 or 6 hours, no gem at all and he didn't get an ore in around 5 mins, so I decided to move it 2 blocks down. 2 secs later, bam, ref rainbow. Moved another of my miners, got a norm tortoise. Standing still I've found ref furys, normal furys, and a super dragon.
So you can do both standing or moving, it won't give you anything better.