Worst Talent

What is a spirit stone? It's a highly sensitive stone found in this world that reacts with the spirit energy present in one's body. Even a single speck of spirit energy will change its colour according to the visible spectrum.

While there are all sorts of spirit stones, their quality is determined by their blue white texture. The more blue they are, like this one, the more sensitive they are, while higher quality stones would be more white with the purest one being chalky white in colour.

Reacting with spirit energy, the stones slowly gain the ability to reflect visible light, turning red, orange, yellow etc based on how much condensed spirit they absorb. And they leave a residue based on the condensing power of the spirit, just like the small red dot that formed before.

The colour determines the realm you are at, the glow of the stone and how much it turns tell your stage in that realm. And the residue tells the innate talent one has for cultivation.