riviere (necklace)
Type of necklace made of multiple gems of similar color and cut strung together. The stones are either all the same size, or gradually increase in size towards the middle of the necklace, and there may sometimes be pendant gems hanging off the main necklace.
The name refers to the French word for "river", because the stones are thought to ‘flow’ around the neck.
Examples
Danbooru post #9101123: Collier de la Reine - example of a very elaborate early rivière.
Danbooru post #3219484