July Birthstone: Ruby, the King of Gems
Ruby holds the title of July birthstone — a status it has held since long before its formal recognition in 1912. As a variety of corundum second only to diamond in hardness, ruby combines extraordinary durability with a depth of red colour no other gemstone can match. This guide covers ruby's gemmological properties, its place in antique jewellery, and what to look for when choosing a ruby ring.
What Is the July Birthstone?
The July birthstone is ruby, a red variety of the mineral corundum (aluminium oxide). Ruby ranks 9 on the Mohs hardness scale, making it the hardest coloured gemstone and an ideal choice for rings worn daily. Its colour ranges from pinkish red to deep purplish red, with the most prized shade known as "pigeon blood" red.
Ruby owes its colour to traces of chromium within the corundum crystal structure. The higher the chromium concentration, the more intense the red. Corundum itself is colourless — sapphire and ruby are the same mineral, distinguished solely by colour. Any corundum that falls below the red threshold is classified as sapphire, including pink varieties. With a specific gravity of approximately 4.00 and a refractive index of 1.762–1.770, ruby is distinctly dense and brilliant for its size.
Why Is Ruby the Birthstone for July?
Ruby has been linked to July across multiple cultural traditions, but the association was formally standardised in 1912 when the American National Association of Jewelers published the first official birthstone list. That list confirmed ruby as July's sole birthstone — a position it has held unchallenged through every subsequent revision, unlike months with multiple assigned stones.
The connection between gemstones and calendar months traces to at least the first century, when the historian Josephus drew parallels between the twelve stones of the High Priest's breastplate and the twelve months of the year. By the eighteenth century, wearing a gemstone matching one's birth month had become common practice across Europe. A widely circulated poem published by Tiffany & Co. in 1870 reinforced these popular associations, with July's verse declaring: "The glowing ruby shall adorn / Those who in warm July are born."
What Does Ruby Symbolise?
Ruby symbolises passion, protection, and vitality. In Sanskrit, ruby is called ratnaraj, meaning "king of precious stones" — a title reflecting its supreme status in Hindu tradition. Medieval European royalty wore rubies as talismans of courage and authority, believing the stone could ward off illness, betrayal, and misfortune.
Ancient Hindu texts associate ruby with Surya, the sun deity, and regard it as the most powerful of the nine planetary gemstones. Warriors in Burma reportedly embedded rubies into their skin before battle, believing the stones granted invincibility. In medieval Europe, ruby signified nobility — its presence in a crown or ring indicated divine favour and legitimate rule. This royal association carried directly into British antique jewellery, where rubies featured prominently in engagement rings, ceremonial pieces, and symbolic gemstone jewellery from the Georgian period onwards.
How Were Rubies Used in Georgian Jewellery?
Georgian jewellers set rubies in closed-back gold settings with foil placed behind the stone to enhance colour and brilliance. These early ruby rings typically featured flat-cut or rose-cut stones in simple collet mounts, often flanked by rose cut diamonds set in silver-topped gold — a construction method characteristic of the eighteenth century.
Foil backing intensified the ruby's colour but also concealed internal characteristics, which means Georgian rubies are frequently more included than their outward appearance suggests. The stones were cut to retain maximum weight rather than maximise brilliance, resulting in irregular shapes that follow the natural crystal form. Gold purity in Georgian rings was typically 18ct or 22ct, giving these ruby rings their distinctive warm, deep yellow tone that complements the red of the stone.
How Did Victorian Jewellers Use Rubies?
Victorian jewellers placed rubies at the centre of elaborate cluster rings, five stone arrangements, and boat-shaped bezels, almost always set in 18ct yellow gold. The period between 1860 and 1901 produced the highest concentration of ruby rings in British jewellery, driven by both romantic sentiment and expanding access to Burmese mines.
Ruby featured in acrostic jewellery, where the first letter of each stone spelled a word — REGARD rings used Ruby, Emerald, Garnet, Amethyst, Ruby, and Diamond. Red carried symbolic weight: it represented passion and enduring love, making ruby engagement rings a deliberate statement of devotion. Britain's annexation of Upper Burma in 1886 opened direct access to the Mogok ruby mines, increasing the supply of fine Burmese stones reaching British workshops. Browse our antique ruby rings and Victorian ring collection to see examples from this period.
How Do Edwardian Ruby Rings Differ?
Edwardian ruby rings moved away from the heavy yellow gold of the Victorian era towards platinum and white metal settings with delicate millegrain edging. The rubies were often smaller but more precisely cut, set alongside old European cut diamonds in designs that emphasised lightness and intricate metalwork over bold colour contrast.
The transition from Victorian to Edwardian design brought open-back settings that allowed light to pass through the ruby from behind — a marked change from the closed-back mounts of earlier periods. Platinum's strength permitted finer prong work, and the knife-edge and filigree styles of the period framed rubies with a delicacy impossible in softer gold. The boat ring remained a popular format for ruby and diamond combinations, with Edwardian examples displaying characteristic scroll gallery work beneath the bezel. For a deeper exploration of how rubies appear across antique periods, read our guide to rubies in antique rings.
Where Do the Finest Rubies Come From?
The Mogok Valley in Upper Myanmar (formerly Burma) has produced the most highly valued rubies for at least seven centuries. Mogok rubies are prized for their intense "pigeon blood" red colour and characteristic silk inclusions that scatter light evenly through the stone, creating a soft internal glow driven by chromium fluorescence.
| Source | Period of Significance | Characteristics |
|---|---|---|
| Mogok, Myanmar (Burma) | 13th century onwards | Intense red, strong fluorescence, silk inclusions |
| Sri Lanka (Ceylon) | Ancient to present | Lighter pinkish red, high clarity, larger crystals |
| Thailand (Siam) | 19th–20th century | Darker brownish red, higher iron content |
| Mozambique | 2009 onwards | Rich red, comparable to fine Burmese examples |
The term "pigeon blood" was first recorded in 1829 to describe the finest Mogok stones. Sri Lankan rubies tend towards lighter, more pinkish tones and often achieve greater clarity than Burmese examples, while Thai rubies carry a darker, more brownish hue due to higher iron content. In antique rings, Burmese origin is the most desirable provenance, though formal gemmological origin testing was not available until the twentieth century. Explore our gemstone ring collection for pieces featuring rubies alongside other precious stones.
How Do You Evaluate Ruby in an Antique Ring?
Colour matters most when evaluating ruby — above clarity, cut, and carat weight. The ideal antique ruby shows a saturated red with minimal brown or orange overtones, maintains its colour under different lighting conditions, and displays the natural inclusions and hand-cut faceting consistent with its attributed period rather than modern machine precision.
Antique rubies were cut by hand to follow the crystal's natural shape, producing cushion cuts, oval cabochons, and irregular mixed cuts different from the calibrated stones of modern production. Inclusions such as silk — fine rutile needles within the crystal — are expected in antique rubies and can enhance the stone's appearance by diffusing light evenly. Heat treatment to improve colour has existed in rudimentary form since at least the medieval period, but industrial-scale electric furnace treatment only became widespread in the 1970s. Rubies in rings predating this period are more likely to be unheated, which commands a premium in today's market.
Which Famous Rubies Should Every Collector Know?
Three rubies hold particular significance. The Sunrise Ruby, a 25.59-carat Burmese pigeon blood stone mounted by Cartier, sold at Sotheby's Geneva on 12 May 2015 for $30.42 million — the highest price paid for a ruby at auction. The Rosser Reeves Star Ruby and the De Long Star Ruby reside in major museum collections in Washington DC and New York respectively.
| Ruby | Weight | Location | Significance |
|---|---|---|---|
| Sunrise Ruby | 25.59 ct | Private (sold Sotheby's, 2015) | World auction record for a ruby |
| Black Prince's Ruby | ~170 ct | Imperial State Crown, London | Red spinel, not a true ruby |
| Rosser Reeves Star Ruby | 138.7 ct | Smithsonian, Washington DC | Largest fine star ruby; Sri Lankan origin |
| De Long Star Ruby | 100.32 ct | American Museum of Natural History, New York | Burmese origin; stolen in 1964, later recovered |
The Black Prince's Ruby in the Imperial State Crown illustrates how rubies and red spinels were treated as the same stone until mineralogists chemically differentiated the two in 1783. The De Long Star Ruby, donated to the American Museum of Natural History in 1937 by Edith Haggin de Long, was stolen in a notorious heist in 1964 and recovered the following year after a ransom was negotiated. Visit the A-Z of Gemstones reference page for detailed profiles of ruby and other precious stones found in antique jewellery.
Frequently Asked Questions
Is ruby the only July birthstone?
Ruby is the sole gemstone assigned to July on both the traditional and modern birthstone lists. Unlike months such as June (pearl, alexandrite, moonstone) or October (opal, tourmaline), July has never had an alternative stone. The 1912 standardisation by the American National Association of Jewelers confirmed ruby as July's only birthstone, and no subsequent revision has added a second option.
How hard is ruby compared to other gemstones?
Ruby scores 9 on the Mohs hardness scale, second only to diamond at 10. The Mohs scale is not linear — diamond is roughly four times harder than ruby in absolute terms — but ruby surpasses every other coloured gemstone in scratch resistance. This exceptional hardness, combined with no cleavage plane, makes ruby one of the most durable stones for daily wear in a ring setting.
What is the difference between ruby and garnet?
Ruby and garnet share a red colour but differ in composition, hardness, and optical properties. Ruby is corundum (aluminium oxide) with a Mohs hardness of 9; garnet is a silicate mineral group with hardness between 6.5 and 7.5. Under magnification, antique rubies display characteristic silk inclusions and a higher refractive index, producing noticeably stronger brilliance and a more vivid red than garnet.
Are rubies in antique rings heat treated?
Rubies in rings predating the 1970s are more likely to be unheated than modern stones. Rudimentary heat treatment has been practised in Sri Lanka and other gem-producing regions since at least the medieval period, but industrial-scale treatment using electric furnaces only became common in the latter twentieth century. A qualified gemmological laboratory can determine whether a ruby has been heated, and unheated stones of good colour command a significant premium at auction.
What does "pigeon blood" ruby mean?
"Pigeon blood" describes the most desirable ruby colour: a saturated, slightly purplish red with strong fluorescence under natural light. The term was first recorded in 1829 in reference to rubies from Myanmar's Mogok Valley. It indicates a narrow colour range combining intense red saturation with a soft, glowing quality caused by chromium fluorescence — not a single precise shade but a quality standard recognised by gemmological laboratories.
Related Reading
- Rubies in Antique Rings — a detailed guide to ruby use across Georgian, Victorian, and Edwardian periods
- Gemstone Symbolism: What Stones Really Mean — the history and meaning behind precious stones in antique jewellery
- Victorian Rings: Romance, Mourning & Empire — the era that produced the greatest concentration of ruby rings in Britain
- Explore our complete guide to gemstones in antique rings — the Gemstones pillar page