I grew up with a sapphire birthstone, so I used to think that all sapphires were blue. Imagine my surprise to learn that sapphires come in a rainbow of colors.
Technically, sapphire is a variety of the mineral corundum. Ruby is also a form of corundum, and the name sapphire is used for any corundum that isn't ruby red. These fancy sapphires can be yellow, pink, green, purple, brown, and just about anything between, even color changing depending on lighting!
Trace elements determine the color. Pure corundum is colorless. If there are trace amounts of iron and titanium, the corundum is blue sapphire. With chromium instead, the corundum is ruby red or pink. The purple color of the sapphire featured in this pendant comes from trace amounts of vanadium.