New vintage tortoiseshell horn bone acrylic bracelet (brwn-blk w tiny triangle)

New vintage tortoiseshell horn bone acrylic bracelet (dark brown-black with tiny triangle) Rare find! I’m not sure what they are made of: lightweight, warm to touch, smooth, glossy but matte texture, opaque-translucent. I’m leaning towards acrylic. Despite the material, it has a very natural and organic appeal. They look like horn or bone or faux tortoiseshell in parts especially when held to the light. Tiny nails pin the links and clasps to the components. New vintage c. 1970s. Silvertone metal fold over clasps and rings. (Not precious silver). Probably acrylic. 2.5” diameter, 22 mm wide x +1 mm thick Group photos show the variety in the collection