The easiest way to find out where the diagrams are is to buy the right map. In this case it will be the "Edwin Greloff's fouth map" which you can buy from Hattori in Novigrad. Of course you can also look for diagrams on your own.
During one of his numerous adventures, Geralt got his hands on a map covered with strange markings. He quickly deduced that they indicated the locations of hidden witcher caches and, intrigued by the chance of discovering long-lost crafting schematics, he set out to find them.
Edwin Greloff's fourth map
[the writing on the map is smeared with dried blood, cannot be read]
[addendum] Map ain't worth shit. Only thing I found were some griffin symbols scratched on the walls. Can see we're not going to get anything worth near enough to pay back the debts that dandy doctor wracked up with us. Good thing he's worm food now. But maybe it would be worthwhile to loot that tomb under Crookback Hills? I doubt our doctor friend would've wasted his time just running around looking for primitive drawings - there's gotta be some treasure about.
Series:
Hattori
Velen / Novigrad
Mastercrafted Griffin School Gear (Whole Armor)
The Skellige Isles
Mastercrafted Griffin School Gear (Steel Sword)
The Skellige Isles
Mastercrafted Griffin School Gear (Silver Sword)
The Skellige Isles
