As you explore Greater Rifts and level up your favorite Legendary Gems, you're likely to hit a point where it becomes harder to level them further. While you can find out your odds of leveling a gem by talking to Urshi after finishing a Greater Rift, knowing these odds in advance can help you plan your Greater Rift-running experience ahead of time, especially if you have limited Greater Rift keys.

Thankfully, jerbookins has created a useful Legendary Gem Calculator for just such a purpose (hat tip: Reddit Diablo). This handy app takes the level of your current Greater Rift key and Legendary Gem as inputs, and determines your odds of upgrading the gem at the current Greater Rift key level and the next three above it.

You can also use it to find out how powerful a Legendary Gem will be at a given level (making it useful for peering into the future of your Legendary Gems’ potential) and what Trial Wave you’ll need to reach in order to generate a specific level of Greater Rift keystone.

After trying the app out for a bit (and seeing what some of my favorite Legendary Gems will look like when powered up further), I can tell it's well put together. It's tremendously easy now to see what kinds of power I might be able to wring out of my Legendary Gems at higher levels. At least, someday!

For those who have tried this app, which feature in jerbookins' creation do you find most helpful? And what other functions would you suggest to make it even more useful?