The September birthstone is sapphire – a gem that’s been cherished for thousands of years. Although the term sapphire usually refers to the blue variety of corundum (ruby is the red variety), this birthstone comes in a rainbow of other colors.

In addition to being the September birthstone, sapphire is also the gem commemorating the 5th and 45th wedding anniversaries. 

The September birthstone has traditionally symbolized sincerity, truth, faithfulness and nobility. For countless centuries, sapphire has adorned royalty and the robes of the clergy. The elite of ancient Greece and Rome believed that blue sapphires protected their owners from harm and envy. Clerics of the Middle Ages wore sapphires because they symbolized Heaven. Ancient Persians believed the earth actually rested on a giant sapphire, which made the sky blue.

Kashmir, Myanmar (formerly Burma) and Sri Lanka are three historically important sources for the September birthstone. Significant quantities of the September birthstone have also been found in Australia, Thailand, Cambodia, Madagascar and the United States (Montana), among other countries in Asia and Africa.

The September birthstone is relatively hard, ranking 9 on the Mohs scale. It has excellent toughness and no cleavage, which is a tendency to break when struck. This makes it a great choice for rings and other mountings subject to daily wear.

Note, though, that sapphires are often treated to improve their color or clarity. Heat treatment is common – and the results permanent – so it is well accepted in the trade. Less common treatments such as lattice diffusion, fracture filling and dyeing may require special care. In some cases, the color induced by lattice diffusion is so shallow it could be removed if the stone was chipped or had to be recut. Fracture-filled and dyed sapphires can be damaged by even mild acids like lemon juice. Before you buy a sapphire, always ask if it is treated and by what method.

Warm, soapy water is always a safe choice for cleaning the September birthstone. Ultrasonic and steam cleaners are usually safe for untreated, heat-treated and lattice diffusion–treated stones. Fracture-filled or dyed material should only be cleaned with a damp cloth.

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[Gemological Institute of America Inc.]