December Birthstones: Three Stones & How to Choose
December has three official birthstones. Turquoise was set in 1912, zircon replaced lapis lazuli as the alternate in 1952, and tanzanite was added in October 2002.
Zircon and cubic zirconia share a similar name and nothing else. Zircon is a natural mineral whose oldest dated crystals run to roughly 4.4 billion years. Cubic zirconia was first made in a lab in the 1970s to stand in for diamond.
Every tanzanite on Earth comes from one deposit near the Merelani Hills in Tanzania, an area of roughly eight square kilometers.
Nearly all jewelry-grade turquoise sold today has been stabilized with wax, oil or resin, because the stone carries close to a fifth of its weight as water and takes in whatever touches it.
The 1912 list swapped ruby and turquoise between July and December. Tiffany's own gemologist objected in print, arguing that people want warm color in winter and cool color in summer, so the trade had it backwards.
Turquoise carried a message in Victorian jewelry. It stood for fidelity and for forget-me-not, and it was set as the scales on the serpent brooches that spread once Victoria made the motif fashionable. Georgian jewelers had been using it the same way for decades before her, down to turquoise cabochons for a serpent's eyes in the 1780s. The Persian mines at Nishapur that supplied all of it have been worked for more than a thousand years and are still producing.
The newest December birthstone has no history like that, because tanzanite is barely older than the people buying it. Prospectors located the deposit in the Merelani Hills in 1967. It reached the market as blue zoisite until Tiffany renamed it tanzanite for the 1968 launch, and in 2002 it became the only stone ever added to the American birthstone list.
Zircon sits outside both timescales. The oldest dated material on Earth is a zircon crystal at roughly 4.4 billion years, close to the age of the planet's first crust. The stone it gets confused with, cubic zirconia, was made in a laboratory in the 1970s.
So December is three stones that share a month and almost nothing else. Turquoise carries the design history, from Victorian serpent brooches to David Webb's sculpted gold. Zircon carries a correction worth making. Tanzanite carries a scarcity claim that happens to be true, which is rarer than the stone. Choosing between them is the real question, and the answer depends on which of those three things you want.
- What Are the December Birthstones?
- Why Does December Have Three Birthstones?
- What Makes Persian Turquoise Different From American Turquoise?
- How Did Jewelers Use Turquoise From Georgian to Mid-Century?
- Is Most Turquoise Treated or Stabilized?
- Is Zircon the Same Thing as Cubic Zirconia?
- Why Was Tanzanite Added to the December Birthstones?
- Which December Birthstone Should You Choose?
- How Do You Care for Turquoise, Zircon & Tanzanite?
What Are the December Birthstones?
December has three official birthstones: turquoise, zircon and tanzanite. Turquoise is the oldest of the three and the one most people picture. Zircon joined the American list in 1952 and tanzanite in 2002. All three are official, and none of them outranks the others.
There is no single December birthstone color, which is the first surprise. Turquoise is opaque. It runs from even sky blue through blue-green to apple green, and the dark veining some stones carry is matrix, the host rock the turquoise grew in. Zircon is clear, and it comes in more colors than its name suggests: blue, honey, orange-brown, red-brown, green and near-colorless. Tanzanite is clear too, a deep blue with a violet second color that comes and goes with the light.
All December birthstones land somewhere near blue, which is why the month still holds together. The three do not compete on look. They compete on how you wear them.
They come from three centuries of thinking, too. Turquoise held December on the older European lists and kept it when the American trade standardized in 1912. Zircon was already a working jewelry stone in the 1800s and got its December slot in the 1952 revision. The tanzanite birthstone is the newest name on the whole calendar, and nobody knew the stone existed before the 1960s.
One piece of housekeeping. Per GIA, turquoise marks the eleventh wedding anniversary and tanzanite the twenty-fourth. Zircon gets no anniversary at all. The full twelve-month picture sits in the birthstone jewelry guide.
Why Does December Have Three Birthstones?
Because the American list has changed twice, and December took both changes. Turquoise was set as December's stone in 1912. Zircon replaced lapis lazuli as the alternate in 1952. Tanzanite was added in October 2002.
The 1912 meeting solved a business problem. Birthstone lists varied by country, by custom, and in practice by whatever a jeweler had in the case. In August of that year the American National Retail Jewelers Association met in Kansas City and set one list for the whole trade. December went to turquoise, with lapis lazuli named as the alternate.
George Frederick Kunz reprinted that exact table a year later. Kunz was Tiffany's vice president, appointed at twenty-three, and his 1891 book Natal Stones is what made a standard list possible. He also disagreed with what the committee had done to December.
The 1912 list swapped ruby and turquoise between July and December. Ruby had held December in the older Western lists, and turquoise had held July. Kunz thought the logic ran backwards, and he said so in print: "the warmer-colored gem was best adapted for a July birth-stone, while the paler turquoise was best suited to a winter month... The contrary, however, is true; for it is in winter that we seek for warmth, while in the heat of summer nothing is more grateful than coolness." He wanted turquoise in July and ruby in December. The list went ahead without him.
Forty years passed before the list moved. The Jewelry Industry Council made four changes at once in 1952: alexandrite to June, citrine to November, tourmaline to October, and zircon for December in place of lapis lazuli. One thread runs through all four, since each new stone was tougher, easier to find, or both. Lapis lazuli is handsome and it is also opaque, soft and rarely faceted. Blue zircon is transparent, bright, and hard enough to hold a crisp facet edge.
Then fifty years of nothing. In October 2002 the American Gem Trade Association added tanzanite, and the trade was not leading the customer there. It was catching up to a stone it had been selling hard for years. That is the whole story behind three names on one month. Two committees, fifty years apart, both decided December needed one more choice.
What Makes Persian Turquoise Different From American Turquoise?
Persian turquoise is prized for even sky blue with little or no matrix. American turquoise is known mine by mine, and several famous ones are famous for the veining Persian buyers tried to avoid.
The Persian source is Nishapur, in what is now Khorasan province in Iran. All the workings sit on the southern slopes of one peak, between roughly 4,800 and 5,800 feet, and the village at the center is Maaden, where everyone mined, cut and sold the stone. An Arab writer named these mines in 1300. Bauer's 1904 survey counted 266 of them working in 1876. Rough was cut en cabochon on site and carried to Meshed, and from there Bucharian merchants moved it to the Russian fairs and out to the wider market.
The mines still run. The old route into the American market does not, since sanctions closed it in the late 1970s. That is part of why true Persian stone in an American case is usually old stone.
American turquoise works another way, because here the mine name does the describing. Bisbee in Arizona gives blue with a chocolate-brown matrix. Kingman gives strong blue, often flecked with pyrite. Sleeping Beauty turquoise, also from Arizona, is the even matrix-free robin's-egg blue the Southwest trade was built on. Nevada's Lander Blue and Blue Gem are collector names. New Mexico's Los Cerrillos deposits, the old Tiffany Mine, fed the Southwest silver trade for generations.
Sleeping Beauty closed to turquoise in August 2012, and the reason deserves to be stated right. The vein was not worked out. The owners chose to run the property for copper as copper prices rose. Everything from that mine came out of the ground before that date, and the supply only shrinks from here.
The color range has chemistry behind it. Copper makes turquoise blue. Chromium and vanadium push it green. Iron pulls it toward yellow, and rare traces of strontium give the blue-violet stones. Silicate content decides how hard and how dense a stone is, which is why two turquoises of the same color can polish nothing alike. Matrix is a preference, not a fault. Fine dark spiderweb veining has its own collectors, and so does clean uniform color.
Egypt was mining Sinai turquoise long before either of these, though much of the Sinai rough faded badly once it left the ground. Filigree's turquoise and tanzanite jewelry covers the range, from even sky blue through heavily veined blue-green.
How Did Jewelers Use Turquoise From Georgian to Mid-Century?
Turquoise moved through five design eras without ever dropping out, and its job changed in each one. It went from a stone of sentiment to an Egyptian Revival color to a Mid-Century statement.
Georgian (1714 to 1837). Turquoise is present but quiet. The clearest survivor is a serpent brooch of about 1780 in the Smithsonian, which sets cut garnets alongside turquoise cabochon eyes. That puts turquoise inside serpent jewelry roughly sixty years before the Victorians made snakes a national habit.
Victorian (1837 to 1901). This is the era that decided what turquoise means. Early and mid-Victorian jewelers used it as a sentiment stone. Sky blue against yellow gold suited the Romantic period, and the stone turns up as cabochons in serpent brooches, as borders around lockets, and in pave forget-me-not motifs. The meaning attached to it was fidelity.
A belief helped. Accounts from the period describe turquoise paling when its wearer fell ill, then coming back under a new owner, and Bauer recorded the idea as still live in 1904. Turquoise does pale from skin oils and sweat, which gave the belief something to stand on. A gem people thought answered its wearer is exactly what a sentiment custom needs.
One correction is worth making, because it comes up constantly. Queen Victoria's 1839 engagement ring from Albert was a gold serpent set with an emerald, her own birthstone. It was not a turquoise ring. What her ring made popular was the serpent, and turquoise then filled that shape across the whole genre, cut small and set as scales.
The named objects are specific. A gold and turquoise bird brooch of about 1850 sits in the Smithsonian, along with turquoise suites from the 1860s and 1870s. The Marens and Co. necklace of about 1855 combines braided gold, enamel, cabochon turquoises and baroque pearls. Carlo Giuliano's Egyptian Revival demi-parure of about 1865, at the Metropolitan Museum of Art, sets turquoise with ruby, rose-cut diamond, enamel and seed pearl. The Burne-Jones dove brooch of about 1895, also at the Met, works gold with coral, turquoise, seed pearls, ruby and enamel.
The construction is checkable. Victorian turquoise was cut en cabochon almost every time, round or oval, because facets add nothing to an opaque stone. A large turquoise usually took a border of small diamonds. Small turquoise cabochons ran the other direction, framing a larger diamond or ruby at the center. Those two habits date a piece before the stone tells you a thing, and Filigree's Victorian jewelry carries both patterns.
Art Nouveau (1890 to 1910). A short chapter for this stone. Turquoise appears mainly for its cutting, grouped with opal and moonstone as a cabochon gem, because the movement had no use for Victorian faceting.
Art Deco (1920 to 1935). Tutankhamun's tomb opened in 1922 and Egyptian Revival followed at once. Turquoise became one color in a scheme: turquoise, lapis lazuli and coral, often with onyx as the dark note. Cartier made scarab brooches, winged-disk brooches and lotus tiara elements in that palette. Georges Fouquet's turquoise, onyx and diamond brooch and his diamond, turquoise and chalcedony brooch-pendant are both in the Victoria and Albert Museum. One fact here matters more than the design history: Art Deco turquoise was almost always natural stone, because stabilizing it was not yet standard practice.
Retro (1935 to 1950). Two dated pieces carry the decade. Cartier made a gold dress clip with lapis lazuli and turquoise between 1935 and 1940, now at the V&A. Ed Wiener made a sterling silver, coral and turquoise necklace in 1948, now at the Met. Coral beside turquoise is the pairing to watch from here on.
Mid-Century (1950 to 1970). Turquoise came back hard, and the order of events is worth getting right. Turquoise use in the American Southwest runs about two thousand years ahead of silverwork there. Silver arrived late. Navajo smiths learned the craft from Hispanic blacksmiths in the mid-1800s, and turquoise was in Navajo silver by 1880. Zuni silverwork grew up separately from about 1872, and its inlay work puts turquoise first and treats silver as the mount. Kunz counted the trade himself in 1917, finding fifty to seventy-five working silversmiths who turned out thousands of turquoise-set rings a year from the Cerrillos deposits.
The haute jewelry version came a generation later and borrowed the language. Tiffany, David Webb and studio designers set turquoise cabochons into sculpted, hammered yellow gold, often beside coral or lapis. Webb founded his firm in 1948, made his first animal bracelet in 1957, and his zebra bangle of 1963 is still the company's logo. He worked large, using turquoise cabochons the size of almonds so the stone could not be missed. That shape, a big cabochon in a heavy gold mount, is the most common turquoise piece left from the period, and it is what most Mid-Century turquoise in estate inventory really is. October's opal and tourmaline pairing went through a similar two-track history.
Is Most Turquoise Treated or Stabilized?
Yes. Nearly all jewelry-grade turquoise sold today has been stabilized, and stone that takes a bright polish on its own is rare.
The reason is porosity. Turquoise never formed as a single crystal. It is a packed mass of tiny grains, and close to a fifth of its weight is water. That structure drinks whatever it touches.
Stabilization means forcing something into those pores. Wax, oil, epoxy and plastic resin all get used. The result is a harder stone that holds its color and takes a polish, which is the whole reason the treatment exists. Plenty of good-looking turquoise cannot be finished without it. Stabilized turquoise is not a lesser stone so much as another kind of stone, and it only becomes a problem when nobody mentions it.
One treatment deserves its own name. The Zachery process, named for James Zachery, uses an electric bath to cut porosity and even out color without adding anything to the stone. It is accepted trade practice, and only a lab can spot it. What it leaves behind is a raised potassium reading rather than anything you can see.
The value order runs untreated, then Zachery-treated, then stabilized, then reconstituted. Reconstituted turquoise is real turquoise ground up and bound in plastic. It is legal, and like every treatment above it, it has to be disclosed. Dyeing is rare in turquoise itself and routine in the look-alikes, so dyed howlite and magnesite account for a lot of what people take for turquoise.
With antique pieces the dates do the work. Nobody was stabilizing stone when Victorian, Art Deco or Mid-Century turquoise was set. A cabochon in an 1870s gold mount is stone that held its color for a century and a half on its own, because there was nothing in it to help.
None of this is new. Pliny knew the finest turquoise lost color to oil and unguents, and he wrote that in the first century. Bauer's own 1904 test was heat: real turquoise cracks apart hard and goes to a brownish-black powder, while a pressed fake just melts and stays blue. Nobody should try that at home, and the jewelry care guide covers the version you can. Filigree's turquoise and tanzanite jewelry runs from antique cabochons through modern settings.
Is Zircon the Same Thing as Cubic Zirconia?
No. Zircon is a natural mineral, zirconium silicate, mined and cut for centuries. Cubic zirconia is zirconium oxide, first made in a lab in the 1970s to stand in for diamond. The names sit close together and nothing else about them does.
The clinching fact is geology. Zircon crystals include the oldest dated thing on Earth, at roughly 4.4 billion years. Zircon survives what destroys almost everything else, which is why geologists use it to date rock. Cubic zirconia is younger than the moon landing.
Zircon also behaves nothing like a fake under a loupe. It is hard, 7.5 on the Mohs scale, harder than quartz. Its specific gravity runs 4.6 to 4.8, the highest of any gem without heavy metals in it, so a zircon sinks fast in a liquid that floats a diamond. Its double refraction is strong enough to double the facet edges when you look down through the table with a loupe. No diamond does that, and neither does cubic zirconia.
Cubic zirconia is younger than the moon landing
The zircon birthstone also has more color range than its name suggests. Bauer's 1904 survey splits the gem stone into hyacinth, an orange-brown to hyacinth-red, and jargoon, the pale straw and near-colorless kind. Green, brown and violet stones exist too. Almost all the old supply came out of Ceylon, from the same gem gravels that gave up sapphire and spinel.
There is a specific and slightly dark chapter here. Heat a hyacinth and it drops its red all at once, coming out colorless or faintly grey with the lustre brighter than before. Those burnt stones were cut as rosettes and sold as "Matura diamonds." Mourning jewelry took them over real diamonds, because the dusky lustre suited the job better. That is a stone chosen for what it looked like, not a stone chosen to pass as something else.
Blue zircon is the modern chapter. In the 1920s, brown Siamese zircon was found to turn a strong blue when heated in oxygen-free kilns. The treated stones hit world markets so fast that Kunz suspected fraud, the same man who objected to the 1912 list. The heating turned out to be a legitimate process on a natural stone. GIA records blue zircon as a real favorite in Victorian England, with fine survivors you can date to English estate jewelry of the 1880s.
Which brings the practical note. Zircon reaches jewelry through estate pieces rather than steady supply, so it comes and goes, and the turquoise and tanzanite collection does not cover it. No other stone would stand in for it honestly. When a zircon does turn up, check the facet edges. The stone is hard, but those edges wear, so a bezel or a sunk mount is worth asking about.
Why Was Tanzanite Added to the December Birthstones?
Because by 2002 the trade was already moving a lot of it. The American Gem Trade Association added tanzanite to December that October, and it was the first change to the American list in fifty years.
The discovery story is not settled, and the honest version beats the tidy one. GIA's own account says blue stones from northern Tanzania were named as the mineral zoisite in 1962, and that prospectors did not find the main source in the Merelani Hills until 1967. GIA names no discoverer. Pala International's record credits Gerhardt of the F.A. Becker firm in Idar-Oberstein with naming it first, as "blue zoisite," and with finding that heat improved the color sharply. A rival name, "tanjeloffite," went around for a while, until Tiffany ended the argument. Henry Platt, the firm's president and Louis Comfort Tiffany's great-grandson, chose "tanzanite" for the 1968 launch. Mining began in 1969.
A third version has a Maasai herder finding the crystals and leading a prospector to them, and it appears in neither of those accounts. It may well be true. The sources that carry the rest of this history do not have it, so it stays a story rather than a fact.
The rarity case is the part that holds up. Every tanzanite on Earth comes from one deposit near the Merelani Hills in the Lelatema Mountains, an area of roughly eight square kilometers. Four mine blocks work it. No other deposit worth mining has been found anywhere, and people have looked hard. Other zoisite turns up in Austria, Pakistan, Mexico and a dozen other places. Tanzanite does not.
Then there is trichroism, which makes cutting tanzanite a decision rather than a routine. Most colored stones show two colors down different crystal directions. Tanzanite shows three, and it is one of the most strongly trichroic gems known. A blue crystal runs blue one way, red-violet another, and yellow-green the third. The cutter picks which face the finished stone shows, and aiming for blue costs weight. Blue stones are valued above violet ones, so a well-cut tanzanite has real work behind it.
Heat treatment is close to universal and worth knowing about rather than worrying about. Natural rough is usually reddish brown. Heating it to roughly 500 to 600 degrees Celsius turns that blue-violet, and the change holds for good. Assume any blue or violet tanzanite has been heated. Unheated blue rough is rare enough to be an event: in 2005 Pala International bought three unheated crystals out of Becker's own collection. They were mined in 1969, the first year of production, and left unheated because the color was already good.
Durability sets where tanzanite belongs. It runs 6 to 7 on the Mohs scale with perfect cleavage in one direction, so the risk is a sharp knock rather than slow wear. Earrings and pendants take almost no impact. A ring is fine in a protected setting and a poor idea in an exposed one. The color also shifts with the light, more blue by day and more violet under a lamp, which puts tanzanite near sapphire in a case without ever being mistaken for it. No synthetic tanzanite exists. The imitations are glass and synthetic forsterite, and neither one survives a close look.
Which December Birthstone Should You Choose?
Choose by how you plan to wear it. Turquoise for color and history in a piece you put on for a reason, tanzanite for clear blue in a protected mount, zircon for brightness.
Take the hardness numbers first, because they decide more than taste does. Turquoise sits at 5 to 6 on the Mohs scale, and it is porous on top of that. Tanzanite runs 6 to 7 with a cleavage plane. Zircon is hardest of the three at 7.5 and brightest, because it has real fire in it.
Those numbers point at different pieces. Turquoise belongs in earrings, pendants, brooches, bracelets and cocktail rings worn for evenings. A cabochon in a bezel is the right modern advice and also the way the stone was set for a hundred and fifty years, which is convenient. What turquoise does not want is to be the ring you never take off. Tanzanite has the opposite habit. It will not slowly dull, but it will chip if something hits it, so earrings and pendants are easy and a ring rides on the setting. Zircon holds a polish well, and its facet edges are the soft point.
Then apply the filter nobody mentions: how old do you want the piece to be. Turquoise is the only one of the three that can be antique at all, and it can be antique across five eras. Zircon can be antique too, and Art Deco and Retro zircon pieces exist in real numbers. Tanzanite cannot be. Nobody knew the stone before the 1960s, so a Victorian tanzanite is not a rare find, it is a wrong label. That one fact settles more December gift decisions than any hardness table.
Color is the last call, and it is personal. Opaque against clear is a bigger jump than blue against blue-violet. Filigree's turquoise and tanzanite jewelry puts both side by side, and the cocktail rings are where the largest turquoise cabochons usually end up.
How Do You Care for Turquoise, Zircon & Tanzanite?
Three stones, three different hazards. Turquoise fears liquids and chemicals, tanzanite fears impact, and zircon fears abrasion and long sun exposure.
Turquoise needs the most care and the least equipment. A soft damp cloth, then dry it right away. No ultrasonic, no steam, no detergent, no soaking. Anything liquid can travel into the pores and stay there, and that includes perfume, lotion, sunscreen, hairspray, chlorine and sweat. Kunz made the point plainly in 1917: the standard warm water, soap and ammonia routine that works on other stones does not apply to turquoise rings. Put turquoise on last and take it off first.
Tanzanite is easier and has one hard rule. Warm water, mild soap and a soft brush are fine. Ultrasonic and steam are not, because a cleavage plane and a fast heat change make a bad pair. Take a tanzanite ring off for anything that involves gripping or lifting.
Zircon takes warm soapy water without complaint. Keep it out of prolonged direct sunlight, though. Bauer recorded that some hyacinths pale or turn browner in sun and only partly come back in the dark, so a stone left on a bright windowsill is being changed.
Storage is the same answer for all three, and it is the step people skip. Separate soft pouches, or separate compartments. Turquoise at 5 to 6 picks up scratches from almost anything harder resting on it, and tanzanite takes a chip from a knock inside a box as easily as one outside. The jewelry care guide breaks cleaning down by stone type, and turquoise is the entry worth going over twice.
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Turquoise & Tanzanite Jewelry
Two of December's three stones in one place, from Victorian turquoise cabochons to modern tanzanite in gold.
Browse December Stones →Cocktail Rings
Where the largest turquoise cabochons end up: heavy gold mounts, Victorian through Mid-Century and modern.
Browse Cocktail Rings →Birthstone Jewelry Guide
The full birthstone calendar with Filigree's pieces for every month of the year.
View the Guide →Three stones, three different distances
December is the only month whose stones sit at completely different distances from us. Turquoise has been mined since the Bronze Age and set continuously through two hundred years of documented design history. Zircon is as old as the planet's first crust and has spent the past fifty years being mistaken for a synthetic it has nothing to do with. Tanzanite was found within living memory, comes from one hillside, and earned its place on the calendar by being wanted. Three stones, one month, and no obligation to pick a favorite on anyone's authority but your own. The full range across both stones we carry sits in the turquoise and tanzanite jewelry.
Ready to Find Your December Stone
From Victorian turquoise cabochons and Mid-Century gold to modern tanzanite, the collection carries two of December's three stones.
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December Birthstones
What color is the December birthstone?
There are three answers. Turquoise is opaque, running from even sky blue through blue-green to apple green, sometimes with dark matrix veining. Zircon is clear and comes in blue, honey, orange-brown, green and near-colorless. Tanzanite is a clear blue with a violet second color that strengthens under lamplight.
Is turquoise durable enough for a ring?
Yes, with judgment. At 5 to 6 on the Mohs scale it is the softest of the three and it is porous, so a cabochon in a bezel is the right construction and evenings are the right occasion. It is a poor choice for the ring you wear through gardening, dishes and hand sanitizer.
Can you wear tanzanite every day?
In earrings or a pendant, yes. In a ring it depends on the setting, because tanzanite has perfect cleavage in one direction and chips from impact rather than wearing down slowly. A bezel or a low protected mount makes daily wear reasonable.
Is zircon a natural stone?
Yes. Zircon is a natural zirconium silicate mineral, and the oldest dated crystals on Earth are zircons. Cubic zirconia is a different substance entirely, a synthetic zirconium oxide first made in the 1970s. Sharing a few letters is the whole connection.
When was tanzanite added as a December birthstone?
October 2002, by the American Gem Trade Association. It was the first change to the American birthstone list since 1952, and tanzanite joined turquoise and zircon rather than replacing either one.
