A a beautiful 4.25mm parti cut sapphire set in a 18kt yellow gold tube on a 14kt 1.1mm yellow gold cable chain. 
A parti sapphire is a type of sapphire that exhibits two or more distinct colors within the same stone, separated by distinct color zoning. This means the colors don't blend together but rather appear in defined bands or sections, unlike the blended hues seen in teal sapphires. The term "parti" comes from the word "partition," highlighting these color divisions.