Starstones are special stones that always remember where they last were, and serve a purpose similar to leaping crystals.
Starstones are used to transport a person to another place, using a beam of light. Lady Gisela states that starstones remember where they last were.
Before leaping crystals were invented, the ancients relied on starstones to move around. Over the years, people began using them less. Eventually, making starstones became a lost art.
Sometime before the series, Lady Gisela needed to settle on an inconspicuous way to teleport to the Nightfall facility. She came up with the idea of starstones, since keeping one was less suspicious than using a leaping crystal.
Lady Gisela inducted the help of an elf named Cyrah Endal. She managed to convince her by threatening the safety of her husband. Cyrah agreed, and Gisela ordered her to make two for her, specifically ones with a blue flash.
Cyrah did as instructed, and was able to craft one. However, on her second one, she messed it up. Before she was able to make a replacement, Fintan grew suspicious at her involvement and had her killed through Gethen.
“The silver-white stone was smooth and oval, but when the light hit it, thin veins of blue shot through in an asterisk pattern”