A Multi-Functional Symbol This symbol is so versatile and widely used that we couldn’t just have one version of it. That just wouldn’t be fitting. Our gold-plated psi necklace can still be worn by a variety of science and math lovers. Whether you’re into math, physics, biology, or astronomy, psi will inevitably pop up and present itself. So, if you’re not into silver, then purchase this gold-plated version. It also makes a great gift for mathematicians, physicists, Greek mythology lovers, and se