It seriously seems to be 30 alt, I mined out a 13 long x 11 wide cave and found diamonds then I mined above that same spot and found more right when I couldn’t mine anymore. That is 11 diamonds in like 5 minutes. Unbelievable. I used the Andoween mine portal (mine 1) dug up to 30 alt and checked it out. I am attaching a chart made by @Stretchious Thanks Stretch! The chart is awesome! !
Update: 1 hour has gone by and I am at 31 gems now.
I’ve done a few large cutouts across both of the mines and find that is pretty random. Some days I find them up near 35ish and other days I find most near lava level. Its good hearing others having good luck down there though! 
How to mine diamonds? I did it this way
-> Get a diamond hammer,
-> Go to Andoweem.
-> Find a plateau, dig straight down
-> Mine at level 14.
~200 rough diamonds per hour.
I’m going to have to try that
200 per hour? How lol. - That’s some extreme luck. (I have a gather alt max stats, diamond hammer etc) I am not the most experienced miner in this thread but its what I do most of the time, and although I’ve hit it lucky once or twice, 200 per hour is NOT the norm :D. I will try that depth and report if that changes.
Personally I shoot for between the min max values and then mine out any ore veins with a diamond hammer to mine around them. I’ve been going in between min/max to be sure I don’t miss many veins, mining a high corridor. I find if there is ore in a diamond rich spot, then there is a chance of diamonds near it.
If you are talking about luck as one of the stats apparently that doesn’t affect diamonds because the diamonds are on a tier 2 planet.
@Slane
No slane I am meaning lucky finding that many seams
Oh makes sense, my bad.
I drowned typing the reply lol
At least it wasn’t walking backwards through a sky portal this time
Are you using gem tools yet? The gem tools don’t mine a single block at a time. Maybe that’s why you thought it was odd he’s mining 200 an hour? Apparently emerald makes tunnels or something, that’s wild.
@slane
My gatherer alt uses diamond hammers with full stats for speed/power and persisting pies (not full crit yet). I don’t use any additional buffs yet, but the rate of clearing rock is good. I prefer diamond hammers for strip mining with sapphire to hit single blocks. I sometimes bring an amethyst as well along with me to hit a two stack ore block. Emerald hits 5 but it makes ugly tunnels and I find it slower overall but it can be good for revealing additional ore seams.
Gem tools are amazing, I have a portal that leads directly into a gem mine if you or anyone ever wants to use it. I use persisting pies to, saves so much durability plus I have the skills to give my tools higher durability. Anyways, if you go to Aquatopia theres a portal that says V&W on it. My portal is up the ramp on the right and says Dalmasca on it. Go in and go through all the portals until you don’t see one then take a right go up the stairs take that portal then the last portal you’ll see leads right into the mine You could always set up a portal at the V&W store and have a way to the mine anytime. I friended the store owners so can easily help you get that set up. I mostly set it up to help others, eventually hooking up more portals so we can easily get to each planet to mine whatever is needed. It is alot of upkeep but its worth it!
Optimal levels are between 5 and 30.
I mine at 17 so I’m directly above lava level. I won’t mine directly into lava this way.
With the update raising the tier of the planet. It means now there is multi dropping diamonds via the luck stat going on. So the rate of gaining diamonds has obviously increased, and the prices on the market dropped.
For anyone wondering on pricing and drop rate. It is still slower than caving but now by a huge amount.
