The September birthstone is sapphire – a gem that’s been cherished for thousands of years. Sapphire is one of the most popular colored stones because of its beautiful blues. It also comes in a rainbow of other colors. Here’s how to pick a stunning one.
The September birthstone, sapphire, comes in a range of colors in addition to the familiar blue. Called “fancy sapphires,” these are violet, green, yellow, orange, pink, purple, black, brown and intermediate hues. Sapphire can be colorless, too. That’s because the gem belongs to the mineral species corundum, which is composed of aluminum and oxygen. In its purest state, corundum is colorless. However, colorless corundum is rare. Most corundum contains trace amounts of additional elements including iron, titanium, magnesium, vanadium, and chromium that replace aluminum in the corundum structure. The coloration of blue and fancy sapphires involves interactions between these impurity elements—sometimes in combination with imperfections in the gem’s crystal structure—that absorb light and impart color into this otherwise colorless mineral.
Blue in sapphire requires interaction between impurities of iron and titanium, whereas chromium is key to the pink in pink sapphires and the red color of ruby, which also belongs to the corundum mineral species. (Red corundum is the only color not called sapphire – it is called ruby.)
Any color of corundum can show a phenomenon called asterism, or the star effect. This phenomenon usually appears as a six-ray star pattern across a cabochon-cut stone’s curved surface when the gem is examined in direct sunlight or with a single intense light. Asterism is caused by the presence of numerous tiny, needle-like inclusions of rutile or hematite oriented in specific directions.
Another interesting variety is color-change sapphire. These fascinating stones appear to be a different color under different lighting conditions, most often going from violetish blue in daylight or fluorescent lighting to deep reddish purple in incandescent light. Their presence adds a special dimension to the options available for the amazing September birthstone.
Sapphire History & Lore
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. The clergy of the Middle Ages wore sapphires because they symbolized Heaven.
The September birthstone was also reputed to have healing powers. Medieval Europeans believed that sapphire cured plague boils and diseases of the eye. It also was thought to be an antidote to poison.
In addition to being the September birthstone, sapphire is also the gem commemorating the 5th and 45th wedding anniversaries.