MAKER'S FORGE (FORGE LANDS)
1) The stone can be found in the southern area of the Maker's Forge; on the Tri-Stone's side.
STONEFATHER'S VALE (FORGE LANDS)
1) You can find the stone in the north-eastern area, the same where you take a Book of the Dead page from and fight a battle with a Bloodless.
WEEPING CRAG (FORGE LANDS)
1) The stone is on the stone arch (looking from Baneswood, not the Stonefather's Vale), not far from where Vulgrim is standing.
BANESWOOD (FORGE LANDS)
1) The stone is hidden inside the small ruins located in the north-west (screenshot 1). When you get there, make your way to the top balcony.
2) The stone is located in the northern part of Baneswood, near the destroyed pillars.
3) You can find the stone in the area that separates Baneswood from the Charred Pass. It's inside the ruins lying alongside the main road, where you also fight one of the Bloodless.
NOOK (FORGE LANDS)
1) The stone can be found in one of the underground chambers, which you don't have to go through while journeying to the Lost Temple. It's the room with two lifts (screenshot 1) with a puzzle that involves rolling a ball into the hole on the upper balcony. Use the lift on the right to go up and locate the secret.
CHARRED PASS (FORGE LANDS)
1) You can find the stone in the north-eastern corner of the Charred Pass, not far from the passage leading to Baneswood. Find the small ruins (screenshot 1) and make your way up to the balcony.
2) The stone is lying on the rocks above the passage leading south, towards the Scar (one of the optional dungeons).
3) You can find the stone within the ruins in the west of the Charred Pass, by the path leading to the Cauldron (screenshot 1). Enter the ruins, go all the way to the top balcony and go through the hole in the wall.
SHADOW'S GORGE (FORGE LANDS)
1) The stone is lodged in the wall right of the entrance to the Shattered Forge, one of the optional dungeons in the game. It's located in the northern part of the Shadow's Gorge.
FJORD (FORGE LANDS)
1) You can find the stone south of where Blackroot is, the current mission's quest giver.
2) The stone is on the rocks along the narrow path leading to Drenchfort, in the south-eastern part of the Fjord.
DRENCHFORT (FORGE LANDS)
1) You can find the stone in the southern part of the central area of Drenchfort, right in front of the large statue and directly above the aqueducts which will be flooded in the course of the main quest.
LOST TEMPLE (FORGE LANDS)
1) The stone is hidden right where you use the Construct golem to launch the chain. It's the southern part of the first large area in the Lost Temple; you don't have to jump down in order to shoot the target.