T6 will get you more gems - but also tougher rocks to break, and then it becomes a 50-50 coin toss with which planet on the server you get. T5 can still be good and if you choose that server should lock in Serp since T5’s only have the one each.
If you really want more emerald than amethyst, you could go with Toxic with this same build and have more of that - only thing being here I use some island biomes to create more shallow water area for the amethyst spots, but there isn’t much that could be swapped out to make it that much better for emerald (which is deep water). But this Corrosive build SHOULD (done well with it on several trials) get you decent emerald while loading you up with amethyst hotspot, which is better than pure emerald spots for other stuff. Keep in mind too, it will probably add in a few other random biomes you didn’t pick.
Also, this build should get you tons of gleam. A couple other notes I’ll throw in.
On caves, far as I can tell so far, just go with Standard Caves 1, seems safest from what I’ve seen. Small caves sounds like it should be good but actually creates a ton of them so they’re a bit of a pain.
Gleam Lake alone
Man-Made Islands - I’ve seen good amethyst spots around these
For the third, Icebergs might be better on a Toxic. I like Beaches though, partly for the looks I admit.
Kong Island (Gives some shallow water area around the edges)
Island Trees - I recommend this because of the farming, it will give you a ton of lustrous wood, trumpet roots, glow caps, and flowers. Even though it is a land biome.
Last pick is tricky: I go Flying Foliage, but could go with Lantern Field… Lantern Field I’ve had mixed results with on gems though, but might be the safer pick.
For the third pick, if you want some decent building land, Giant Slice will give you some. Otherwise, might go Floating Island Paradise. I still need to test Bridge Islands.
Floating Shrapnel - This will light up your sovereign like a Christmas Tree with the gleam, if your results are like mine.
Sky Pattern - Might be better for the gem spots overall though.
Gleam Rain could be a safe pick, I tried it once and didn’t see any at all.