This is a natural Aquamarine stone bead, really big faceted marquiz cut at 10x30 mm, made into a pendulum with a simple silver chain. The top bob is a faceted Aquamarine coin shaped bead. It's approximately 6 1/3 inches long
I always ritually craft my pendulums on a Monday or Wednesday when the Moon is Half Full, and this one is also from a batch that I made on the Spring Equinox, March 18, 2023, for even more balance.