There’s a guy on trung with nasty prices for everything but not in coin convertors.
Aenea’s prices:
Obviously it’s full at the moment but she’s not been playing much. Every gem has a buyer on trung paying over 30C except topaz atm.
But you would be better off going to a planet with more commercial activity like gyosha or alder or something tbh.
Find a portal to the TNT megahub. There you can pop in and out of portals for every T1, T2, T3, and T4 planet in one spot. It’s almost 40 planets.
I do see from researching this that people are trying to buy topaz as low as 20c right now. TBH you’ld be better of to toss them in a shop stand if you don’t want to find someone paying 30c or more.