These are color change Nd+ laser garnets (Nd:YAG), which are light violet, pink or peach in normal lighting and turn a pale yellow under fluorescent illumination. Each individual stone is labelled with its carat weight and letter in the photo and they can be purchased individually.
This is next-gen Nd+ laser YAG, a type of lab created garnet used widely in lasers. The original Nd YAG has been used in lasers since 1964, but the old formula only contained Nd and was all the same shade of purple-pink. This material is a newer, more advanced formulation with extra elements like Ce added to broaden the accepted wavelengths for lasing thus making the lasers more powerful, and these add another dimension to the color. In natural light they vary from purple to pink to peach, and under fluorescent lighting they change to near colorless or a pale orange-yellow. These stones have been compared to Mahenge garnets and pastel pyropes.
Note this color change is the exact opposite of Holmium laser YAG, and if you pair the two you can do a neat color swap magic trick.
With a hardness of 8.5 it is ideal for use in all kinds of jewelry.
