An aletheia crystal is a crystal used to hold memories.
Aletheia crystals are many-faceted crystals the size of a child's hand. They have a smooth, stone-like surface.
Aletheia crystals are used to capture, store, and even physically transport the stored memories. When the crystal is dormant, the memories contained within it flash across its surface. Once activated through a Latin incantation, the crystal begins to glow until it releases a focused beam of light, which acts as a projector and casts moving images across a nearby wall.
In September 2012 an aletheia crystal was discovered at Blackthorn Hall by Ty and Livvy Blackthorn and Kit Herondale. The crystal contained the memories of Annabel Blackthorn from her trial in the early 19th century.
- Lord of Shadows (first appearance)
- Aletheia crystals appear to darken the room they are in when activated, as the one found in Blackthorn Hall extinguished surrounding candles when activated by the warlock Shade.
- Aletheia crystals are named after the Greek goddess of truth, Aletheia.