[thejeff]

No. Once you rack up 80 pearls, you can wish for gems, alchemize and have 100 pearls. Put 20 aside (or don't alchemize them), use the other 80 to wish again. If you have another Wish caster, in 4 turns of wishing you can start him wishing for gems as well.
The limitation is how many Wish casters you can create. Assuming you don't have native S4+ casters, you have to Wish for an S4, Forge RoS, Skullcap and Coin and empower twice. That's 80S+40S+10S+10S+10E + whatever it takes to empower from 4 to 6 and another 80 pearls to start him wishing.
Then it's 40 gems/turn. Which means you can ramp up the next wisher in half the time...

If you think that's too expensive, it's still a free wish every 4 turns.