Memory Stone

Memory stones are palm sized magical crystals that are capable of storing a creature's memory. The holder of a stone can focus and transfer their memory to the crystal, and thereafter has a vague recollection of the contents of the memory, but cannot remember it in detail anymore. Once a memory stone has stored a memory, the crystal appears to have a flickering glow inside of it.
A creature can view a stone's stored memory by holding it, and focusing on it. They enter a semi-catatonic state and experience the memory as the original owner did. This can be done as many times as desired.

Manufacturing process

Memory stones are carved from a specific type of crystal that grows incredibly slowly. Many stones were crafted when their magical properties were discovered, and their manufacture nearly entirely halted when the supply of crystals ran out.
The particular cut, size, and quality of the crystal can affect some of its properties, such as length and clarity of the memory.
Memory stones are still crafted in exceedingly small amounts, and even lower quality stones remain somewhat uncommon.

Statistics

Nailara

Memory Stone

Wondrous Item Magical Uncommon [Divination]

A memory stone is a gem cut from a rare crystal that was once much more common. As wizards of old crafted the memory stones, the crystals that had been growing for millenia were soon all consumed. Now, few are crafted, and unused stones are incredibly hard to find.
You can use an action to focus on the stone and store a memory in it. You are no longer able to remember the memory afterwards. Once a memory stone stores a memory, it can never again be used to store a new memory.
You can use an action to smash the memory stone, freeing the memory it stores. The creature who originally placed the memory is able to recall the memory once again.
Additionally, the memory can be viewed without destroying the stone by using a focus suitable for scrying (e.g. a crystal ball, font of water, etc worth 1,000g). The memory plays back in real time, from the point of view of the original creature.
Memory stones come in a variety of qualities that can determine their effects. Examples are:

Clarity

Cracked: A cracked memory stone may play back its memories with missing chunks, and visuals even more distorted than hazy stones. The original creature may retain chunks of the memory.
Hazy (Uncommon): Memories viewed from cracked stones are dream-like, and often only hold detail for what the original creature was focusing on.
Clear (Rare): Memories viewed from clear stones hold much greater detail, but still have some blurring of the original creature's periphery vision.
Flawless (Very Rare): Memories viewed from flawless stones hold perfect detail. Additionally, flawless memory stones counteract memory magic such as the Modify Memory spell, and store the original true memory even if the original creature was not aware it had been modified.

Size

Small: Stored memories can be up to one minute long.
Medium: Stored memories can be up to one hour long.
Large: Stored memories can be up to one day long.

Soul of Edda by Richard Romare

Rarity

Uncommon - Rare