This design is called Sea Orb. Mirage beads are thermo-sensitive and continuously change color, ranging from black (when cool) through all the hues of the rainbow as they warm with body temperature and climate.
This is a 4.5 inch long strand of ten polymer beads that are 12.4mm round beads.
Although polymer beads are very durable, I don't recommend submerging them in water.
Product code 127.