1) Stonemason's Memory
Availability: chapter 3
The exact location: The collectible can be found after you reach the scriptorium in the underground ruins [Underground Ruins - Scriptorum]. Find the interactive row of books here and interact with it, press the button and explore the secret chamber.
2) Charity's Memory
Availability: chapter 2
The exact location: Along your way to the foundry's main building, Garrett will reach a big square with a small cottage on it [Old Foundry - Dust Yard]. Make it over at the back of the cottage and find a hole in its roof to jump inside. The Ring is in one of the drawers of the big table.
3) Soldier's Memory
Availability: chapter 4
The exact location: The Collectible is at one of the levels of the keep [The Keep - Boiler Level] and you can find it right before you use the elevator Look around for a corpse and examine it.
4) Child's Memory
Availability: chapter 5
The exact location: The Ring can be found in one of the side corridors, at the lower level of the old prison [Old Prison - Reformation]. Of course, you need to keep precautions here, because the prison is being occupied by monsters (however, none of the creatures should be in the side passage).
5) Elder's Memory
Availability: chapter 7
The exact location: While exploring the Graven Lair [The Hidden City - Graven Lair], stop after you reach the Rotunda's entrance. You need to make it over onto the Southern balcony (a rope or a crate climb), to find the collectible on it.
6) Braggart's Memory
Availability: chapter 6
The exact location: The Collectible can be found in the lab [Northcrest Manor - The Baron's Laboratory] that you visit towards the end of the chapter. walk into the hall with the big machine and climb up the stairs, to the very top. Extend the rope, using the rope arrow, and make it over onto the next ledge, where the ring is.