Bicolor/Party color system
Some gemstones exhibit multiple colors within a single stone; two colors are called bicolor, three colors are tricolor, and multiple colors are called particolor. Some are clearly separated, while others have a gradation, so I think these are gemstones that give you a sense of their individuality.
Karatz GemMagazine
" Bicolor gemstone "
Benitoite 0.066ct loose
¥14,800
Bicolor tourmaline 1.198ct loose
¥14,800
Bicolor tourmaline 0.961ct loose
¥25,800