An Ice Stone was first seen in Not Caving Under Pressure!, where Sophocles's Charjabug found one while helping to fix up a cave inhabited by a group of Alolan Sandshrew, revealing that the cave was in fact an Ice Stone mine where Sandshrew gather to evolve. The leader of the Sandshrew pack, a giant Sandshrew, touched the stone and proceeded to evolve into an Alolan Sandslash. Later, after exiting the cave, Charjabug was revealed to have found another Ice Stone, which Sophocles gave to Lillie. She asked Snowy if it wanted to use the stone to evolve, but Snowy didn't feel ready for it yet, so Lillie decided to hold on to the stone in case Snowy ever changed its mind.
The Ice Stone was first revealed by a picture on the official Spanish Pokémon website on October 4, 2016. However, the picture was quickly removed due to the stone not having been previously announced.
Eevee is the only Pokémon that can evolve using the Ice Stone that is not a regional form.