I've heard you need to upgrade all of the cursed tools before you can get Mythic Stones. I've upgraded all of of my tools then I found another cursed rod while digging in the spring mine. Do I have to get this upgraded too before I can get Mythic Stones?

I got them all blessed. It's just that I found another cursed rod. Do I have to get that blessed too?

It is not uncommon to discover additional cursed tools. You do not need to continue un-cursing them all however. Once you have a complete set of Blessed Tools then the Mythic Ore becomes unlocked and you will be able to mine for it.

Really? Great
How hard is it to get a Mythic Stone?

As long as you have a complete blessed set, it doesn't matter how many other cursed tools you get (I have 2 fishing rods and a hammer). Go to the Spring mine (near the hot springs) and dig to the 60th level, save on the 59th in one slot so you can reload if there aren't any Mythic stones on the first try. Break all the boulders, if it is there it is a Black branch. If you don't find one, reload level 59 and go down again. I have found none and as much as 4 on one pass. You have to be patient and willing to keep trying the level to get the stones.

quote Shelley

As long as you have a complete blessed set, it doesn't matter how many other cursed tools you get (I have 2 fishing rods and a hammer). Go to the Spring mine (near the hot springs) and dig to the 60th level, save on the 59th in one slot so you can reload if there aren't any Mythic stones on the first try. Break all the boulders, if it is there it is a Black branch. If you don't find one, reload level 59 and go down again. I have found none and as much as 4 on one pass. You have to be patient and willing to keep trying the level to get the stones.