September Birthstone: Sapphire
Sapphire, the September birthstone, is the blue variety of the mineral corundum and one of the most durable gemstones set in antique rings. Ranking 9 on the Mohs hardness scale, it has adorned ecclesiastical rings, engagement bands, and royal jewellery for centuries. This guide covers what makes sapphire September's designated stone, where the finest examples originate, and what to consider when choosing an antique sapphire ring.
What Is the September Birthstone?
The September birthstone is sapphire, the blue variety of the mineral corundum (aluminium oxide, Al₂O₃). It ranks 9 on the Mohs hardness scale, making it the second hardest natural gemstone after diamond. Its blue colour results from trace amounts of iron and titanium within the crystal structure, with deeper blues containing higher iron concentrations.
Corundum crystallises in the trigonal crystal system, has a specific gravity of approximately 4.00, a refractive index of 1.762–1.770, and no cleavage — meaning the stone resists chipping during daily wear. These physical properties made sapphire a practical favourite of Victorian and Edwardian jewellers for rings intended to last a lifetime.
The term "sapphire" alone refers to blue corundum. Red corundum is classified as ruby. All other colours — pink, yellow, green, orange, violet, and colourless — are known as fancy sapphires. This distinction matters when evaluating antique pieces, as both sapphire and ruby belong to the same mineral family yet carry different valuations.
| Property | Value |
|---|---|
| Mineral | Corundum (Al₂O₃) |
| Crystal System | Trigonal |
| Mohs Hardness | 9 |
| Specific Gravity | 4.00 |
| Refractive Index | 1.762–1.770 |
| Colour Cause (Blue) | Iron and titanium trace elements |
Why Is Sapphire the September Birthstone?
Sapphire has been linked to September since at least the early modern period, and the association was formalised in 1912 when the National Association of Jewelers in the United States published the first standardised birthstone list. The connection draws on centuries of belief in sapphire's protective and spiritual qualities.
The birthstone tradition traces its roots to the Breastplate of Aaron, described in the Book of Exodus as bearing twelve gemstones representing the twelve tribes of Israel. By the medieval period, scholars linked specific stones to calendar months, and wearing the corresponding gem was believed to channel its particular virtues during that month.
Sapphire held particular status in medieval Europe. Clergy wore sapphire rings because the blue colour symbolised heaven and divine favour. The Greeks and Romans believed sapphires protected their owners from harm and envy, while Persians held that the earth rested upon a giant sapphire whose reflection coloured the sky.
These associations with loyalty and wisdom endured into the Victorian period, when Queen Victoria received sapphire jewellery from Prince Albert and the stone became fashionable for engagement rings amongst the aristocracy. Sapphire also marks the 5th and 45th wedding anniversaries.
What Colours Do Sapphires Come In?
Sapphires occur in every colour except red, since red corundum is classified as ruby. Fancy sapphires include pink, yellow, green, orange, violet, and colourless varieties. The rarest and most valuable fancy sapphire is the padparadscha — a pink-orange stone whose name derives from the Sanskrit and Sinhalese word for a lotus blossom.
Blue sapphires range from pale cornflower to deep midnight tones. The most desirable stones show a saturated medium-to-deep blue with strong brilliance and even colour distribution. Kashmir sapphires are distinguished by a velvety quality caused by microscopic inclusions that scatter light within the stone, producing a soft, almost luminous appearance.
Star sapphires display a six-pointed star across their domed surface when cut as cabochons. This optical effect, called asterism, results from three sets of needle-like rutile inclusions intersecting at 120-degree angles within the crystal. The Star of India — a 563.35-carat blue star sapphire from Sri Lanka held by the American Museum of Natural History — is the most recognised example of this phenomenon.
| Variety | Colour | Distinguishing Feature |
|---|---|---|
| Blue sapphire | Medium to deep blue | Iron and titanium chromophores; most widely recognised |
| Padparadscha | Pink-orange | Rarest fancy sapphire; traditionally Sri Lankan origin |
| Star sapphire | Any colour with asterism | Six-rayed star from rutile needle inclusions; cabochon cut |
| Yellow sapphire | Pale to golden yellow | Iron trace element; found in antique dress rings |
| Pink sapphire | Light to vivid pink | Chromium trace element; borders ruby classification |
Where Do the Finest Sapphires Originate?
Three regions have historically produced the most celebrated sapphires: Kashmir in northern India, Sri Lanka (formerly Ceylon), and Myanmar (formerly Burma). Each source yields stones with distinct characteristics, and geographic origin significantly influences a sapphire's value at auction and in the antique trade.
Kashmir sapphires emerged in approximately 1881 when a landslide in the Himalayas, at around 4,600 metres elevation near Soomjam in the Pádar District, exposed a pocket of exceptional blue crystals. The mines operated intensively until approximately 1887, yielding stones now regarded as the finest sapphires ever discovered. Their distinctive velvety cornflower blue remains the benchmark against which all blue sapphires are measured. A pair of Kashmir sapphire earrings sold at Sotheby's Geneva in November 2013 for over $8.3 million.
Sri Lanka has supplied sapphires continuously for over 2,000 years. Ceylon sapphires typically present a lighter, more brilliant blue with high transparency. The 423-carat Logan Sapphire in the Smithsonian's National Gem Collection — confirmed unheated by GIA — demonstrates the exceptional quality these deposits produce. Burmese sapphires from the Mogok Valley are known for a deep, saturated royal blue.
| Origin | Typical Colour | Key Characteristic |
|---|---|---|
| Kashmir | Velvety cornflower blue | Microscopic inclusions create soft, luminous quality |
| Sri Lanka (Ceylon) | Light to medium blue | High transparency; over 2,000 years of continuous mining |
| Myanmar (Burma) | Deep royal blue | Intense saturation; Mogok Valley provenance |
| Madagascar | Medium blue, wide range | Major modern commercial source |
| Australia | Dark blue-green | Higher iron content; tends towards inkier tones |
How Were Sapphires Used in Victorian and Edwardian Jewellery?
Victorian and Edwardian jewellers set sapphires in cluster rings, five-stone bands, solitaire designs, and navette settings. The stone's hardness made it ideal for everyday wear, while its blue colour carried associations with fidelity and heaven that appealed to both the Church and those choosing engagement rings.
During the Victorian era (1837–1901), sapphires frequently appeared in engagement rings as symbols of faithfulness. Queen Victoria herself received sapphire pieces from Prince Albert, and this royal association strengthened the stone's desirability amongst the middle and upper classes. Victorian sapphire rings typically feature 18ct yellow gold settings with cushion cut sapphires surrounded by rose cut or old European cut diamonds.
The Edwardian period (1901–1915) brought a shift towards platinum and more delicate metalwork. Sapphires appeared in millegrain settings, scrollwork designs, and five-stone arrangements alternating with diamonds. The contrast between blue sapphire and white platinum created the refined visual effects that defined Edwardian jewellery taste.
Sapphires also featured in acrostic rings, where the first letter of each stone spelled a word. In DEAREST rings, the S stood for sapphire. These coded sentimental messages made sapphire a staple of Victorian romantic jewellery alongside rubies, emeralds, and diamonds.
What Should You Look for in an Antique Sapphire Ring?
Evaluate colour first — a vivid, evenly distributed blue without dark patches or colour zoning indicates a quality stone. Check the setting for period-appropriate construction: hand-cut collets, slight asymmetry, and tool marks on the interior of the band. Hallmarks provide reliable evidence of date and origin.
Colour is the primary valuation factor. The most desirable antique sapphires show a saturated medium-to-deep blue that holds its hue under different lighting. Stones that appear black in low light or wash out to pale grey in daylight are less prized.
Clarity expectations differ for antique stones. Fine silk inclusions — rutile needles within the crystal — can enhance a sapphire's appearance by softening its colour and improving light distribution, which gives Kashmir sapphires their velvety quality. Heavy inclusions reduce transparency and value, but moderate silk is a positive attribute.
The setting itself helps authenticate a ring's period. Victorian claw settings in 18ct yellow gold, Edwardian millegrain bezels in platinum, and hallmarks from British assay offices all contribute to dating. A ring retaining original stones and readable hallmarks commands a premium over one with replacements. Browse our collection of antique sapphire rings to compare examples, or explore our antique Victorian ring collection for era-specific pieces.
How Can You Tell if a Sapphire Has Been Heat Treated?
Laboratory certification from GIA or Gem-A is the only reliable method of confirming whether a sapphire has been heat treated. Gemmologists examine internal inclusions under magnification — unheated sapphires retain delicate silk inclusions and intact crystal formations that dissolve or alter when subjected to high temperatures.
Heat treatment became commercially widespread in the 1970s, when Thai dealers began heating Sri Lankan geuda — milky corundum — to produce deep blue material. Over 90% of sapphires on the market today have been heated, according to GIA, making unheated stones with good colour genuinely scarce.
In the antique market, this question carries particular weight. Sapphires in genuine Victorian and Edwardian rings predate commercial heating and are almost invariably unheated. Unheated stones of comparable colour command prices up to double those of heated equivalents. A gemmological report confirming "no indications of heating," paired with hallmarked dating, provides assurance of both the stone's natural state and the ring's age. Discover our Edwardian ring collection for period sapphire settings.
For a deeper look at sapphire across all periods, read our guide to sapphires in antique rings. Consult our A-Z of Gemstones for every variety found in antique jewellery.
Frequently Asked Questions
Is sapphire suitable for an engagement ring?
Sapphire is one of the strongest choices for an engagement ring. At 9 on the Mohs scale, it is second only to diamond in hardness and has no cleavage, meaning it resists chipping under impact. Sapphires withstand daily wear without surface abrasion, which is why Victorian and Edwardian jewellers set them in engagement rings intended to last generations. The stone's longstanding association with fidelity makes it a particularly fitting choice for this purpose.
What is the difference between a blue sapphire and a Ceylon sapphire?
"Ceylon sapphire" refers to geographic origin — Sri Lanka, historically known as Ceylon. Ceylon sapphires tend towards a lighter, more brilliant blue than stones from Kashmir or Burma, though Sri Lanka produces sapphires across a wide colour range. The term carries a trade premium because of Sri Lanka's reputation as a sapphire source spanning over 2,000 years of continuous mining, and because many Ceylon sapphires remain unheated.
Are antique sapphires more valuable than modern ones?
Antique sapphires in original period settings often command higher prices than comparable modern stones because they predate commercial heat treatment. An unheated sapphire with good colour, held in a hallmarked Victorian or Edwardian mount, combines gemmological rarity with historical provenance. Both factors drive demand amongst collectors and can push prices well above those for modern heated equivalents of similar size and colour.
What does sapphire "silk" mean?
Silk refers to fine, needle-like inclusions of the mineral rutile distributed within the sapphire crystal. In moderate quantities, silk softens the stone's colour and creates a desirable velvety appearance — the defining characteristic of Kashmir sapphires. Heavy silk reduces transparency and dulls the stone, but fine silk is considered a positive attribute and a strong indicator that the sapphire is natural and unheated.
Can sapphires be colours other than blue?
Sapphires occur in pink, yellow, green, orange, violet, and colourless varieties, all classified as fancy sapphires. The rarest is the padparadscha, a pink-orange variety whose name derives from the Sanskrit word for lotus blossom. Only red corundum is classified separately as ruby. Fancy sapphires appear in antique jewellery — particularly Victorian dress rings — though blue remains the predominant colour in period pieces.
Related Reading
- Sapphires in Antique Rings — a detailed guide to sapphire ring styles, settings, and buying considerations across every era
- Victorian Rings: Romance, Mourning & Empire — the period when sapphire engagement rings gained widespread popularity
- June Birthstone: Pearl, Alexandrite & Moonstone — the previous entry in our birthstone series
- Read our complete guide to gemstones in antique rings — the Gemstones pillar page