|Owners:||Jacob Grimm II (known)|
|Usage:||To protect the user/owner from everything and anything - making them almost indestructible|
|Appearances:||The Everafter War|
In chapter five of book 7, Jacob Grimm uses an invulnerability stone against a dragon. He was initially going to use the Amulet of Roona, though his niece was accidentally in possession of it at the time. The dragon blasted fire at him and turned his body into a piece of charcoal. Sabrina and Daphne were sure that he was dead - until the charcoal revealed just to be an outer shell with Uncle Jake safe inside of it.
The invulnerability stone Jacob used was described as "a dark-green crystal" that glowed when in use. It is unknown whether different invulnerability stones are different colors.