September Birthstone: Sapphire’s Meaning, Color & History

Those born in September claim one of the most regal gems of all: the deep, velvety blue sapphire. A symbol of wisdom, loyalty, and royalty for centuries — and the choice for some of the world’s most famous engagement rings — sapphire is a fittingly noble birthstone for the start of autumn. And here’s a delightful surprise: sapphire isn’t only blue. At Gems Lore, here’s your complete guide to the September birthstone: its meaning, royal history, its rainbow of colors, star sapphires, treatments, and how to choose one as a gift.

A quick frame first: gemstone meanings come from tradition and symbolism, not science — and sapphire’s legacy is among the most royal of any gem.

What Is the September Birthstone?

The birthstone for September is the sapphire, in both modern and traditional lists. There’s no rival for the month — sapphire stands alone, most famous in deep blue, though it occurs in nearly every color. As one of the four classic precious gemstones (alongside diamond, ruby, and emerald), it lends a September birthday genuine prestige.

About Sapphire: The Basics

Remember July’s ruby? Here’s the twist: sapphire and ruby are the same mineral. Both are varieties of corundum. Red corundum is called ruby; corundum of every other color is called sapphire. So a blue sapphire and a red ruby are geological siblings, separated only by the trace elements that color them — iron and titanium give sapphire its classic blue.

Quick facts:

• Mineral: Corundum (every color except red)
• Color: Most famously blue; also pink, yellow, green, purple, orange, and colorless
• Hardness: 9 on the Mohs scale — second only to diamond, superb for everyday wear (see our gemstone hardness chart)
• Main sources: Sri Lanka, Myanmar, Madagascar, Australia, and historically Kashmir
• Good to know: extremely durable and water-safe; most sapphires are heat-treated

That 9 hardness — just below diamond — makes sapphire one of the toughest gems available, perfect for engagement rings and heirlooms built to last lifetimes.

Sapphire’s Many Colors

Many people are surprised to learn sapphire comes in a whole rainbow. Any color of gem corundum that isn’t red is a sapphire:

• Blue sapphire — the classic and most famous, from light to deep “royal” blue
• Pink sapphire — increasingly popular and romantic
• Yellow sapphire — sunny and golden
• Green, purple, and white (colorless) sapphires — beautiful and often more affordable
• Padparadscha — a rare and prized pink-orange sapphire, named after a lotus blossom, among the most valuable of all

Sapphires that aren’t blue are called “fancy sapphires,” and they let a September baby choose almost any color while still claiming the month’s stone.

Sapphire’s Royal History and Meaning

Sapphire has been associated with royalty, wisdom, and the divine for thousands of years. Ancient Persians believed the sky itself was blue because it reflected a giant sapphire on which the earth rested. Medieval clergy wore sapphires as a symbol of heaven, and royalty across Europe prized them for protection, wisdom, and divine favor — believing the stone guarded against envy and harm.

In the modern era, sapphire became the royal engagement stone. The blue sapphire ring given to Princess Diana — and now worn by Catherine, Princess of Wales — is one of the most famous pieces of jewelry in the world, sparking a lasting fashion for sapphire engagement rings.

Traditionally, sapphire symbolizes:

• Wisdom and truth — long the stone of sages and clergy
• Loyalty and faithfulness — a fitting choice for engagement and commitment
• Royalty and nobility — the gem of kings, queens, and the heavens
• Protection — believed to guard against harm and envy

The Color and Quality of Sapphire

For blue sapphire, color is the key value factor. The most prized is a vivid, velvety, medium-to-deep “royal” or “cornflower” blue — rich and saturated, but not so dark it loses life. The legendary Kashmir sapphires, with their soft, velvety blue, set the historic standard and command extraordinary premiums, as do fine Burmese and Ceylon (Sri Lankan) stones.

Stones too dark, too pale, or too grayish are less valued. Clarity matters too, though some inclusions are expected; in fact, certain fine silk-like inclusions create one of sapphire’s most magical effects (see star sapphires below). Origin can significantly affect value, which is why certification noting origin matters for fine stones — see our how to buy gemstones online guide.

Star Sapphires

One of sapphire’s most enchanting forms is the star sapphire. When the stone contains fine needle-like inclusions (called silk) aligned in a particular pattern, and it’s cut as a smooth dome (cabochon), light reflects to form a glowing six-rayed star that glides across the surface as the stone moves. This effect, called asterism, turns an “included” stone into something extraordinary — proof that in sapphire, even inclusions can be a gift.

Why Most Sapphires Are Treated

Every sapphire buyer should know: the vast majority of sapphires are heat-treated to improve their color and clarity. Heating deepens and brightens the blue and can dissolve unwanted inclusions — a standard, long-accepted practice when disclosed. Untreated sapphires with fine natural color are rarer and command premiums.

There are also more extensive treatments (such as diffusion or fracture-filling) that a reputable seller should disclose, as they affect value and care. For any valuable sapphire, ask about treatment and request certification, and learn to spot imitations in our how to spot fake crystals guide.

Lab-Grown Sapphires

As with other precious stones, lab-grown sapphires are widely available — real sapphires, chemically identical to natural ones, grown in a lab at a fraction of the price. Sapphire was among the first gems to be synthesized over a century ago. Lab-grown stones offer excellent color affordably, while natural sapphires keep the rarity, history, and value retention that synthetics don’t. We weigh the trade-offs in our lab-grown vs natural gemstones guide.

Famous Sapphires

Sapphire’s royal status is written in its most legendary stones. The Star of India, a 563-carat grayish-blue star sapphire housed at the American Museum of Natural History, is one of the largest and most famous star sapphires in the world — and survived a sensational 1964 jewel heist. The Logan Sapphire, a stunning 423-carat blue stone at the Smithsonian, is among the largest faceted gem-quality sapphires on display anywhere. And the Stuart Sapphire and St. Edward’s Sapphire are historic stones set into the British Crown Jewels, their stories woven through centuries of royal history.

Perhaps most famous of all in the modern day is the 18-carat blue sapphire engagement ring that belonged to Princess Diana and is now worn by Catherine, Princess of Wales — a single piece of jewelry that revived sapphire engagement rings around the world. Together, these stones show why sapphire has been the gem of royalty and the heavens for so long.

Who Is the September Birthstone For?

Beyond September birthdays, the month’s stone connects to the zodiac signs that span it: Virgo (August 23 – September 22) and Libra (September 23 – October 22). Sapphire’s associations with wisdom and balance are often considered a fine match for thoughtful, harmonious Libra.

Sapphire is also the traditional 5th and 45th wedding anniversary gemstone, making it a meaningful milestone gift — see our anniversary gemstones by year guide.

Gift Ideas for a September Birthday

Sapphire is a regal, durable, and versatile gift — with options across colors and budgets. A few ideas:

• Blue sapphire jewelry — a ring, pendant, or earrings; its 9 hardness makes it superb for everyday wear, and royal blue is endlessly elegant.
• A fancy-color sapphire — pink, yellow, or purple for something distinctive and often more affordable than fine blue.
• A sapphire engagement ring — following the famous royal tradition, durable enough for a lifetime.
• A star sapphire cabochon — magical and unusual, with its glowing six-rayed star.
• A lab-grown sapphire — vivid color at a gentle price, ideal for a larger or cleaner stone on a budget.

For more inspiration across stones and budgets, see our crystal gifts for a birthday guide.

Caring for Sapphire

Sapphire is one of the easiest fine gems to care for, thanks to its toughness. At 9 on the Mohs scale it’s extremely hard, durable, and water-safe — warm soapy water and a soft brush keep it brilliant, and it doesn’t fade. A couple of notes: if a sapphire has been fracture-filled or diffusion-treated, avoid harsh cleaning and ultrasonic cleaners, so know your stone’s treatment first. Store sapphire separately, since at 9 hardness it can scratch most other gems. For general guidance, see our how to cleanse crystals guide.

Frequently Asked Questions

What is the September birthstone?

The September birthstone is sapphire, in both modern and traditional lists. It’s a variety of corundum and one of the four classic precious gemstones, most famous in deep blue — though it comes in nearly every color.

What color is the September birthstone?

Sapphire is most famous as blue, but it occurs in pink, yellow, green, purple, orange, and colorless too. Non-blue sapphires are called “fancy” sapphires; the rare pink-orange padparadscha is especially prized.

What does the September birthstone mean?

Sapphire traditionally symbolizes wisdom, truth, loyalty, royalty, and protection. It has been the gem of clergy and kings for centuries and is a classic stone of faithful commitment.

Are sapphire and ruby the same stone?

Essentially, yes — both are the mineral corundum. Red corundum is ruby; corundum of any other color is sapphire. The trace elements that color them are the only difference.

Are sapphires treated?

Most sapphires are heat-treated to improve color and clarity, a standard and accepted practice when disclosed. Some receive more extensive treatments. Untreated fine sapphires are rarer and command premiums.

Why is sapphire popular for engagement rings?

Sapphire is extremely durable (9 on the Mohs scale), beautiful, and steeped in royal tradition — famously the choice for Princess Diana’s and Catherine’s ring — making it both practical and meaningful for a lifetime piece.

What is a padparadscha sapphire?

Padparadscha is a rare and highly prized sapphire in a delicate pink-orange color, named after the lotus blossom. Its unusual blend of pink and orange makes it one of the most valuable and sought-after of all fancy sapphires.

Where to Go From Here

Sapphire is a magnificent birthstone for September — regal, durable, and available in a rainbow of colors, with a history fit for kings and queens. Whether you choose classic royal blue, a fancy color, or a magical star sapphire, you’re celebrating with one of the world’s most treasured gems.

Explore every month in our birthstones by month chart, learn how gems like sapphire form in our how gemstones are formed guide, see the month before in our August birthstone guide, and discover next month’s gem in our October birthstone guide. Explore more any time here at Gems Lore.

Are you a September baby? Tell us your favorite sapphire color — classic blue or a fancy shade — in the comments.