September's Birthstones – Sapphire and Moonstone

The month of September has two lovely birthstones: the modern birthstone for September is the luscious sapphire, one of the 'Big 4" gemstones, and the traditional birthstone for September is the mystical moonstone. Find out what September's birthstones can mean for you.

September Birthstone Info Graphic

What is a sapphire?

A sapphire is a gemstone quality variant of the mineral corundum. While sapphires are typically thought of as blue, the corundum mineral comes in other colours too, which are known as the fancy sapphires. Fancy sapphires can be yellow sapphire, pink sapphire, green sapphire etc., but never red. Red sapphires are known as rubies! The ruby was once thought to be distinctly separate gemstone, but modern techniques have proven it to be the red variant of corundum – in other words, sapphire!

Star Sapphire Showing Six-Point Asterism

Sapphires often have needle-like inclusions called rutile, decreasing the transparency of the gem. The most valuable sapphires are the ones with the least inclusions, except for when those inclusions form a star-like pattern called asterism. Asterism will most often present as a six-pointed star, though some sapphires have been found with 12-pointed stars. Sapphires with asterism are usually polished en cabochon to display the star, whereas transparent sapphires are cut to show their sparkle.