What Is the Birthstone for July?

Ruby became July’s official birthstone in August 1912, when the National Association of Jewelers set the modern list at its convention in Kansas City.

The committee allowed only clear, see-through gems, because the list was built to serve the mother’s ring, a band set with a row of small stones. It has changed since. Alexandrite joined June and citrine November in 1952, tanzanite became a December alternate in 2002, and spinel became an August alternate in 2016, which is a quiet joke. Spinel wore ruby’s name in European treasuries for six centuries before it got a month of its own.

July is unusually settled. Ruby holds the month in the modern American list, the older pre-1912 list, the British list of 1937, the Tibetan mystical list, and the Ayurvedic list. The British list came from the National Association of Goldsmiths. Most months carry alternates and arguments. July does not.

Kunz disagreed anyway. He did more than anyone to sell Americans on birthstones, and his 1913 book gave the new list its scholarly weight. He wanted ruby in December and turquoise in July, and his reason was the weather. “It is in winter that we seek for warmth, while in the heat of summer nothing is more grateful than coolness,” he wrote. He lost.

Ruby carries other dates. It marks the fortieth wedding anniversary, and a separate tradition gives star ruby to the fifty-second. In the Hindu Navaratna, ruby is Manikya, the stone of Surya the sun, set at the center of the nine planetary gems. Ruby is also the same mineral as sapphire, September’s stone, which makes July and September the only two months in the birthstone calendar that share a mineral.

Why Is Ruby Called the King of Gemstones?

The title is a translation, not a sales line. Sanskrit texts call ruby ratnaraj, king of precious stones, and ratnanayaka, leader of precious stones. A third term, padmaraga, names the color: red as the lotus.

The ranking had teeth. The texts describe a four-tier system sorting red stones by caste, and a Brahmin stone was never to touch a lesser one, since contact spoiled its virtue. Someone was grading four shades of red by eye long before anyone could measure a refractive index.

Greek and Roman writers both reached for fire. Around 300 BCE the stone was anthrax, burning coal, because held up to the sun it took the color of one. Natural History later put carbunculus first among the fiery red stones, with a second name, acaustos, meaning it will not burn, since fire left the stones unchanged.

In Burma the belief turned surgical. Accounts describe rubies cut into the flesh so they would become part of the body and turn away spear, sword, and gun.

The sharpest record comes from a head of state weeks from death. In 1584, Ivan the Terrible showed his gems to an English envoy and stopped at the ruby. It was "most comfortable to the hart, braine, vigar and memorie of man," he said. Ruby was medicine to him, not decoration, and he was running out of time to test it.

What Makes a Ruby Red?

Ruby is corundum, which is aluminum oxide. A few chromium atoms take the place of aluminum in the crystal, and that is the red. The same mineral with no chromium is sapphire.

The amounts are small. Burmese material runs about 97 percent alumina and 1 percent iron oxide, with traces of silica. The first synthetic experiments proved the link: three to four percent potassium chromate in the melt gave ruby red, and more pushed the crystals violet.

The numbers explain the design history that follows. Hardness is 9, second only to diamond at 10. Specific gravity is near 4.0, heavy enough that ruby sinks in liquids that float most other gems. The refractive index runs from 1.757 to 1.779.

Ruby is also strongly dichroic, which hands the cutter a decision. Look down the optic axis and the color is a deep red-violet. Look through a side face and it is much lighter. The table has to sit close to the basal plane or the stone comes out pale, whatever the rough was worth. A dichroscope settles it in seconds. The old trade called the deeper stones masculine and the lighter ones feminine, a color grade dressed up as a gender.

Where red stops being ruby is a judgment, not a measurement. GIA calls corundum ruby only when red is the leading hue and the saturation is high enough. A clearly pink stone is a pink sapphire, the same chemistry with less chromium. No number divides them, which is why one lab can call a stone a ruby and the next a pink sapphire. Filigree’s ruby collection holds pieces on both sides of that line, and one product description notes rubies with a pink cast rather than a deep red.

What Is Pigeon’s Blood Ruby?

Pigeon’s blood is an optical event, not a spot on a color chart.

Two things happen at once. Inside the stone, fine rutile needles called silk scatter the light, which cuts the dark zones a faceted stone normally flashes as you tilt it. The stone also glows red under the ultraviolet in ordinary daylight, and that glow covers whatever dark zones are left. The result looks lit from inside rather than reflected. Richard Hughes of Lotus Gemology calls it “the glowing embers of a fire.” That lands a few words from where carbunculus was reaching.

Low iron is the price of entry. Mogok’s marble-hosted stones are unusually iron-poor, so the glow survives. Iron kills the effect, so high-iron material from Thailand and Cambodia glows weakly or not at all. Those stones can hold a purer red body color and still look duller in the hand, which is why shopping from a color chart fails.

The trade description is old. By 1904 the top color was on record as “deep, pure carmine-red,” what dealers compared to the blood of a freshly killed pigeon. The phrase goes back to Chinese accounts of the Qing-Burmese gem trade around 1680, older than most of gemology’s vocabulary.

Burmese dealers never used it as a single label. It sat at the top of a five-step scale. Ko-twe, pigeon’s blood, a glowing straight red, rare even at Mogok. Yeong-twe, rabbit’s blood, darker and bluish. Bho-kyaik, a deep hot pink, and the color the British preferred. Leh-kow-seet, light pink, bracelet quality. Ka-la-ngoh, a dark red so unhappy the name means roughly a stone that would make even a dealer cry. Most Mogok rubies lean purple, and true straight-red ko-twe is rare from any source, Mogok included.

Lotus Gemology sorts fine ruby into four modern types tied to iron and glow rather than to poetry: Pigeon’s Blood, Royal Red, Hot Pink, and Fuchsia, each linked to certain origins. A lab’s pigeon’s-blood call is made against that lab’s own master stones, and labs hold different masters. It names a color range, not a fixed chemistry.

Where Do the Best Rubies Come From?

Mogok, in upper Burma, has set the standard for more than eight hundred years. Every other source is still described by how it differs from Mogok.

The Mogok Stone Tract sits about 210 kilometres northeast of Mandalay, roughly 1,500 metres up. Gem-bearing ground covers about 180 square kilometres inside a tract ten times that size. The geology explains the color: dolomitic limestone cooked where igneous rock pushed into it, with the deposits forming while the Himalayas rose. Miners dig the weathered residue on top, called byon, a brown-yellow clay four or five feet thick in the valleys and deeper on the hillsides. Digging is ancient here. By the sixth century locals paid the government about three kilograms of stones a year, and the crown took the tract from Shan control in 1597.

Tavernier gave Europe its first real account in 1676. He placed the mines at Capelan, twelve days from Ava, the capital of Pegu, and recorded the fact that governs the early history. The king kept every stone above a set size. That monopoly held market supply thin, and Tavernier reckoned only a fraction of the ground’s output was ever sold. Above five or six carats, he noted, the trade treated ruby as the scarcer stone, a ranking that held into the early 1900s.

The law had teeth and a loophole. Anyone who found a stone over one hundred ticals had to hand it to the Financial Department or die. So finders broke big stones up, which cost the government more than it gained. Local geology said rubies ripen in the earth, passing from colorless through yellow, green, and blue to red when fully ripe. Wrong as geology, exact as description. It is what a miner saw come out of one wash of byon: corundum in every color the mineral makes.

The British took Burma in 1886, and a London syndicate worked the tract on a yearly payment to the Indian government. Mogok in 2026 needs stating flatly. Private mining was banned and the trade nationalized in 1969, then made legal again in 1992. United States sanctions on Myanmar Gems Enterprise, put back after the 2021 coup, still stand. The Ta’ang National Liberation Army took the town during the civil war, and an 11,000-carat rough ruby was reported nearby in April 2026. A Burmese ruby entering the market now carries provenance questions that one already sitting in a 1930s setting does not.

Mozambique reset the market. Hughes calls Montepuez, found in 2009, “the world’s richest ruby deposit.” Within six years, finding a fine ten-carat ruby went from nearly impossible to picking one of a dozen. Mozambique stones lack Mogok’s purple undertone and glow better than Thai material, so Hughes puts them “somewhere in between.” The 2026 picture is not simple abundance. Gemfields has postponed auctions and reported falling premium-grade yields at Mugloto because of illegal mining.

The rest of the map sorts by iron and by rock. Vietnam’s Luc Yen region, found in the late 1980s, is marble-hosted like Mogok and was the first source to challenge Burma on color and glow together. Madagascar came on in stages, Vatomandry in 2000 and Didy in 2012. Its Andilamena stones hold orange monazite crystals that Mozambique stones do not, which is how a lab tells them apart. Tajikistan’s Snezhny deposit, found in 1979, sits high in eastern Badakhshan, where the balas-ruby mines Marco Polo visited in the 1200s also sat, the root of the whole spinel mix-up.

How Has Ruby Jewelry Changed Through the Eras?

Each era set ruby by what its tools allowed and what its taste would accept, and those decisions left signatures you can still read off a piece.

Georgian (1714 to 1837). Georgian rubies carried messages more often than size. The acrostic ring is the clearest case. REGARD spelled out in stones: Ruby, Emerald, Garnet, Amethyst, Ruby, Diamond. A longer DEAREST version ran to seven. Only someone who knew the code could read it, which was the point. The form began in the Georgian period and peaked under Victoria, so most acrostic rings that survive are Victorian. Ruby’s job here was to supply an R. The stone that had spent two thousand years being called the lord of gems was put to work as a letter.

Ruby held the most formal seat in British jewelry too. The English Coronation Ring, the Wedding-Ring of England, is a table-cut ruby of violet tone, its flat face engraved with a St. George’s cross, ringed by twenty-six diamonds, and jointed so it could be refitted to each new monarch. The queen consort’s ring set a ruby among sixteen smaller ones, chosen because the ruby stands for faithfulness.

Georgian settings were closed at the back and often foiled, because the light in the room was candlelight and a stone needed help. A French ring of the late 1700s in the Metropolitan Museum, accession 198716, puts gold, silver, diamonds, rubies, and glass in one piece with no rank among them. The workmanship was the subject, and paste sat next to ruby without shame.

Victorian (1837 to 1901). Victorian designers used ruby as one color in a scheme rather than as the subject. Carlo Giuliano’s Egyptian Revival demi-parure of about 1865, Met accession 682823, sets ruby with turquoise, rose-cut diamond, enamel, and seed pearl, where the ruby is there for color and nothing else. Reinhold Vasters, in Aachen, set ruby with emerald and baroque pearl in Renaissance revivals convincing enough to pass as real sixteenth-century work for decades.

The motif that put rubies where everyone could see them was the serpent. Albert gave Victoria a serpent ring in 1839, and the form ran for sixty years. Jointed gold bodies that move against the wrist, enamel over the head and tail, rubies set as eyes. Filigree’s Victorian serpents follow the convention. A jointed 18k snake necklace with rubies and blue enamel, and a bracelet with rubies, pearls, and pale blue enamel over a jointed body.

Edwardian (1901 to 1915). Ruby mostly sat this era out. The garland style ran on platinum, diamond, and pearl, and the all-white palette let in very little color. One piece is worth the whole section anyway. In 1913 Henri Lavabre built a diamond and ruby tiara for Cartier, now in the Victoria and Albert Museum as O153154. The British government accepted it in lieu of inheritance tax in 2015. The museum lists its rubies as cabochon-cut synthetics. Hold onto that. It does real work two sections from here.

Art Deco (1920 to 1935). Art Deco made ruby structural. Calibre cutting shaped stones to fill exact channels, and ruby became the most common calibre stone for two reasons. At 9 on the Mohs scale it survived a grinding process that cracked softer gems. And its color ran even enough that forty to sixty shaped stones in one bracelet still read as a single field of red. What Deco wanted from ruby was not peak pigeon’s blood. It wanted agreement.

Cartier ran the other way with Tutti Frutti, known in the house as Hindu jewelry: carved Mughal-style rubies, sapphires, and emeralds massed with diamonds in platinum. Many of the carved rubies in pieces like the 1928 Collier Hindou were centuries-old Mughal work bought from Indian dealers rather than cut new.

The high-water mark is Van Cleef and Arpels’ Mystery Setting, the serti mysterieux, patented in 1933. Each stone is grooved on two edges so it slides onto a hidden gold rail, leaving an unbroken plane of color with no metal showing. Ruby and sapphire were the founding stones because softer gems cracked during the grooving. Emerald was never a candidate. Two of the century’s most demanding techniques exist because ruby is hard.

Retro (1935 to 1950). The 1942 War Production Board order sent platinum to the military and pushed ruby into gold. Cabochons came back harder than in any period since the medieval. Big cabochons cut from silk-bearing Mogok rough showed a star, so star rubies became fashionable for the first time in the modern era.

Retro also hands estate buyers the most useful dating fact in ruby jewelry. Japan held Burma from 1942 to 1945 and cut Mogok off, so ruby jewelry from those three years is more likely to hold Ceylon or Thai stones than Burmese. The patriotic red, white, and blue pieces of the war years lean toward the lighter, hotter reds the trade called bho-kyaik. Supply drove part of that, and the color read better against enamel and yellow gold.

Verdura built Maltese cross cuffs for Coco Chanel out of her own rubies and emeralds. And both Cartier and Van Cleef used small synthetic rubies as calibre accents during the shortage. A concession to scarcity, and the second half of the authentication story.

Mid-Century (1950 to 1970). A 1938 follow-on patent lifted the flat-surface limit, and Van Cleef carried the Mystery Setting onto three-dimensional forms. The ballerina clips are the result: a dancer’s tutu in calibre-cut ruby, bodice and tiara in diamond, no metal visible in the skirt. The 1951 ZIP necklace, thought up by the Duchess of Windsor and built by Van Cleef, used ruby or sapphire as the teeth of a working zipper. It converts into a bracelet. David Webb set cabochon ruby eyes into hammered gold animal bangles. Bulgari mixed ruby with emerald and turquoise while the French houses built suites in one color.

Filigree’s Mid-Century rubies sit in that same figural wit. A coiled 18k cobra ring with a ruby, a ruby-and-pearl spider on a gold web, a matador jacket charm with a ruby and four emerald accents. Channel-set and French-cut eternity bands descend straight from Deco calibre work, and they run through Filigree’s ruby collection in platinum, 14k, and 18k gold.

How Can You Tell If a Ruby Is Real?

The question is about two thousand years old, and it stays hard because ruby has been impersonated by more stones, for longer, than any other gem.

Pliny already found it hard. “Nothing is harder than the attempt to distinguish the varieties of this stone,” he wrote, and then listed the frauds of his own market. Opaque stones made to look see-through with foil behind them. Dull stones steeped in vinegar for fourteen days so they would shine for as many months. Plain glass, which gave itself away on a grindstone. Hardness testing is the oldest ruby test still in use. It just destroys the answer.

Then there is spinel, which did not so much copy ruby as take its name. Balas-ruby, the spinel out of Badakhshan, was medieval Europe’s most admired prestige stone until diamond cutting improved enough to unseat it. Dante used balascio in the Paradiso as an image of divine light. Nearly every famous large ruby in a European treasury before the modern era is a spinel, the Black Prince’s and the Timur among them. Scholars suspected the truth early. A text attributed to Aristotle, written between the seventh and ninth centuries, already grouped ruby, sapphire, and Oriental topaz as one mineral in different colors. Suspicion is not a test, and the tests came much later.

The working tests arrived in the nineteenth century. Old texts said the Lychnis picked up bits of thread and straw when rubbed or warmed in the sun, and in 1865 C.W. King verified that electrical trick in spinel and balas ruby, which separated both from almandine garnet.

Synthetic ruby arrived while those tests were still current, and the dates get misreported. In the 1880s Fremy fused alumina with potassium carbonate, barium fluoride, and potassium chromate at 1,500 degrees Celsius for a week. He got thin flat crystals under half a carat with the same properties as natural ruby. Auguste Verneuil’s flame-fusion process is the one that reached industrial scale. He began experiments as early as 1886 and had a working result by 1892. He left sealed notes with the Paris Academy of Science in 1891 and 1892 to claim priority without giving away the method. He announced the process in 1902 and published the full detail in 1904. Any date in the 1880s for the announcement, a figure that circulates widely, is wrong.

Which brings back the tiara. In 1913, eleven years after Verneuil went public, Henri Lavabre set cabochon-cut synthetic rubies in a diamond and ruby tiara for Cartier. Whether a ruby is natural is not a new worry about new fakes. It has been live in the best workshops since the technology existed, and it was handled then the way it should be handled now, by saying so in the record.

Telling them apart under magnification is simple once you know where to look. Flame-fusion material shows curved growth lines, following the curve of the boule it grew on, plus gas bubbles that are often round or teardrop-shaped. Natural corundum shows straight, angular growth zoning that follows the six-sided crystal, plus mineral inclusions and rutile silk. Without silk there is no scattering, and without scattering there is no inner glow. A flawless, perfectly even red with nothing inside it is a warning sign, not an achievement.

The buyer’s version is short. Get a current report from a recognized lab and read it for three things. Species, where the word you want is natural rather than synthetic. Treatment. And origin, if the report determines it.

What Should You Know About Ruby Treatments?

More than nine in ten newly mined rubies are heated. The treatment is permanent and disclosed, and the distinctions worth learning are between heat and the processes that put something into the stone.

Heat leaves a record in the silk. Rutile needles partly dissolve and break into trains of tiny droplets that still trace the old pattern. Long, dart-shaped needles mean an untreated stone. Broken droplet trails mean heat. Heated stones also often pick up a chalky glow under short-wave ultraviolet, close to unknown in untreated corundum. None of that is a consumer test. It is why a lab report is worth paying for.

Flux healing is the treatment that changed the market. Borax-class fluxes dissolve the surfaces of a fracture and grow new corundum inside it as the stone cools, sealing breaks plain heat cannot close. More than 95 percent of faceted ruby entering world markets since the 1990s is flux-healed Mong Hsu material. Under magnification it shows as dark patches of leftover flux inside the healed break.

Lead-glass filling is a different thing. High-index glass fills the fractures and improves apparent clarity a great deal, and it gives itself away as an oily flash under angled light. The glass is soft and hates heat and jeweler’s acids, so a lead-glass-filled ruby cannot be worked on, cleaned, or repaired the way an untreated stone can. Beryllium diffusion, done above 1,800 degrees Celsius, changes color in a thin surface layer. Both have to be disclosed, and both are worth asking about.

Oiling is the treatment nobody mentions. Burmese traders soak rough in oil at the mine, and it is almost never disclosed downstream. A hot point, a soldering iron run at 400 to 500 degrees under a microscope, brings it back out.

Unheated stones carry a real premium and it has grown. Since 2008, Chinese buyers have outnumbered Americans in the Thai gem market, and that demand prefers untreated material. Heated is not damaged, though. It is stable, permanent, and standard for decades. Undisclosed is the problem, not treated.

What Styles of Ruby Jewelry Are There?

Ruby’s cutting history runs backwards from the way gem histories usually go. Burmese stones were worked as cabochons for centuries before Europe faceted them, often hollowed underneath and filled with gold to hold the color. The cabochon never went out of use.

Faceting buys less on ruby than on diamond. Corundum splits light into colors very little, so there is no prismatic fire to release and the facet plan built for diamond returns nothing. Step cuts, trap cuts, and mixed cuts serve ruby as well as a brilliant does. What you want from a ruby is depth of red across the whole face, and broad flat facets deliver that better than fifty-seven small ones.

Star rubies need the cabochon, and the mechanism is exact. Three sets of rutile needles sit at 120 degrees to each other along the crystal’s axes, and each set throws light back along one line. The three lines cross and make six rays. The cutter sets the base parallel to the plane of the needles and gives the dome height, and a few degrees of error slides the star off center or kills it. This is the same silk that makes the inner glow in a fine faceted stone. A star and pigeon’s blood are two results of one inclusion.

Deco’s calibre work survives as the channel-set and French-cut eternity band. Square, French, or baguette rubies run all the way around a shank and the metal disappears between them. Filigree’s ruby wedding bands are built on that geometry in platinum, 14k, and 18k gold, in full and half eternity.

Tennis formats set a different problem. The hard part in a necklace holding a hundred or more rubies is not the setting work. It is finding that many stones that agree with one another. Ruby’s hue and saturation vary far more from stone to stone than a diamond’s do, and the eye catches one mismatch in a line at once. A 15.01-carat tennis necklace in the collection runs 116 rubies at 3.0mm each, a color-matching job before it is a goldsmithing one. And the cabochon holds its place now for the reason it always did. It shows silk as glow, not as a flaw.