How is the life on hit effect from Life Gems calculated?

When you apply green gems (Life Gems) to weapons, you gain a percentage of life on hit. The actual description on the life gem item is "Weapon: Increase Health stolen by x%" (depending on the level of the gem). What does this percentage correspond to? Is it based on my total health? Or is it based on the weapon damage?

I have not played the game, but from doing some looking online I believe it is based on your weapons attributes, you may be assuming incorrectly the "Increase health stolen by x%".

Lets say that it's 20%. Instead of it being 20% more than your current life steal, I think it may just add on that 20%. So in your comment when you heal with a regular sword, that has 0% life on hit, you are still gaining health because the life gem increases your life on hit by 20%, meaning you now heal for 20% not 20% more than before.

You can test this out if you are able to see how much you are healing/how much damage you do. With the regular sword, the amount healed should be the % of the damage from the life gem.