Each month of the calendar year has its own designated birthstone (and birth month flower), and the stone for September is none other than the sapphire. Here’s what to know about this beautiful birthstone, according to crystal experts.

The meaning behind birthstones.

While the official birthstones we know today weren’t selected until the early 1900s, the tradition of birthstones has been around for centuries.

In the book of Exodus (28:17-20), it’s written that 12 gemstones were fixed on the prophet Aaron’s breastplate. “There were 12 stones, one for each of the names of the sons of Israel, each engraved like a seal with the name of one of the 12 tribes,” the Bible reads.

Birthstones also have roots in Western astrology and Ayurveda, according to founder and educational director of the Love and Light School of Crystal Therapy Ashley Leavy. She previously explained to mbg that the reason the National Association of Jewelers standardized the official birthstones in 1912 was because there were so many birthstone options across various traditions.

Today, birthstones are popular gifts for everything from birthdays to holidays to anniversaries and more.

The September birthstone: sapphire.

The birthstone for September is none other than sapphire, known for its rich color and gorgeous glimmer. As crystal expert and co-founder of Energy Muse Heather Askinosie explains to mbg, sapphires are part of the corundum variety of gems. They have a hexagonal crystal structure and are very, very hard. Sapphires are primarily sourced from India, Sri Lanka, the state of Montana, Western Africa, and Australia, she adds.

In terms of being a birthstone, blue sapphire is typically thought of as the most popular variety, though Askinosie notes sapphire can also be green, yellow, pink, black, and white. (The word sapphire actually comes from the Latin saphirus and the Greek sapherios, which both mean “blue.”)

“For millennia sapphires have been used for healing rituals, astrological prophecy, and alchemy,” Askinosie says, adding that some say sailors believed that sapphires would protect them from drowning at sea, and the medieval kings would wear them around their necks as talismans for protection.

Meanings & symbolism of sapphires.

According to crystal expert and founder of Goldirocks Yulia Van Doren, sapphire has been revered as the “Wisdom Stone” since ancient times. It helps us to “connect with our higher self and our inner empath, who sees the bigger picture, acts from a global perspective, and walks in someone else’s shoes,” she previously told mbg, adding that sapphire is all about making choices with everyone’s best interests at heart.

Along with wisdom, Askinosie notes that the sapphire also represents serenity, spiritual truth, and mental clarity. “It helps to restore balance in the body, builds confidence and self-expression, and it also helps to aid in communication,” she adds.

Van Doren explains that Virgos and Libras born in September, in particular, would do well to keep Sapphire close, “to help you stretch your compassion muscles, empower your better self, and keep small-minded, fear-based thinking at bay.”

And it’s worth noting that different-colored sapphires have some distinctions in their meaning. As Askinosie tells mbg, blue sapphire is thought to be aligned with the planet Saturn, which is all about self-discipline and organization.

Green sapphires, she says, are associated with clarity and compassion, while yellow sapphires are believed to bring wealth. Pink sapphires can help to open the heart, and black sapphires are associated with protection.

There’s a reason sapphires have stood the test of time as a highly sought-after crystal—they’re beautiful, come in a variety of colors, and have strong spiritual properties. September babies, consider yourself lucky!