The Sparkling Stone (Japanese: かがやくいしSparkling Stone) is a Key Item introduced in Generation VII and the raw material needed to create a Z-RingSM or Z-Power RingUSUM. They are given to the island kahuna by the tapu to turn into a Z-RingSM or Z-Power RingUSUM and then gifted to worthy Pokémon Trainers. Rarely, some Trainers may be given one directly by the tapu instead, as is the case with the player.
The player receives a Sparkling Stone from Tapu Koko in recognition of their bravery in protecting Nebby from a swarm of wildSpearow. After the player defeats Hau for the first timeSM or simply returns to Iki TownUSUM, Hala recognizes the stone, and upon realizing that the player has been recognized by the guardian deity of Melemele Island, offers to refine it. The player receives the finished product, a Z-RingSM or Z-Power RingUSUM, after completing the ceremony battle with Hau.
Another, unobtainable Sparkling Stone is given to Hapu by Tapu Fini when the former is made the island kahuna of Poni Island. She later fastens it into her own Z-RingSM/Z-Power RingUSUM. This Sparkling Stone is colored brown, unlike the whiteSM/blackUSUM one the player received earlier.
A stone entrusted to you by a Pokémon that has been venerated as a guardian deity in the Alola region. There is said to be some secret in how it sparkles.
In The Wild Full-Power Pose of Fire, Kiawe was revealed to own a Z-Ring, which he received as a Sparkling Stone from Tapu Lele five years earlier. In order to prevent Sun from using Inferno Overdrive against him again, Gladion had his Type: Null shatter Kiawe's Z-Ring when the latter attempted to lend it to Sun, leaving only the Sparkling Stone intact.