December Birthstone: Turquoise, Zircon and Tanzanite

By Lisa Chen, Founder · July 12, 2026

Short answer: December has three official birthstones — turquoise, zircon and tanzanite — and most jewelers add blue topaz as an easy-to-find fourth option. They all lean blue, which is why they get lumped together, but they behave very differently once they are on your hand. This guide walks through what each stone actually is, how hard it really is, and which ones can take everyday wear.

The three official December birthstones

Most months get one birthstone. December got generous. The lists kept by gemological bodies like the GIA and the American Gem Society name three: turquoise, zircon and tanzanite. All three are blue-to-violet, which is part of why December is sometimes called the "blue birthstone" month.

Turquoise is the old guard. It has been prized for thousands of years and is the traditional December stone, the one your grandmother would have recognized. Zircon joined the modern list in 1952, when it replaced lapis lazuli. Tanzanite is the newcomer: it was only discovered in 1967, in a tiny patch of ground near the Merelani Hills in Tanzania — still the only place on earth it is mined. The American Gem Trade Association added it as a December birthstone in 2002, the first change to the U.S. birthstone list since 1912. So depending on which list you read, "the December birthstone" can honestly mean any of the three.

Wait — is zircon the same as cubic zirconia?

This is the single most common mix-up in the December lineup, and it is worth clearing up before you shop. No, they are not the same thing, and the names are a genuine trap.

Natural zircon is a real mineral, zirconium silicate, that forms in igneous and metamorphic rock. It has been used in jewelry for centuries, and its fire is strong enough that colorless zircon was historically a diamond stand-in. Cubic zirconia is entirely different: zirconium oxide, a lab-grown synthetic created specifically to imitate diamond, inexpensive and mass-produced. The two share three letters and almost nothing else. A stone sold as a "December birthstone" should be natural zircon; anything labeled cubic zirconia or CZ is the simulant. I like cubic zirconia when it is named honestly — we use it in some of our own pieces — but calling it zircon, or letting a shopper assume it is a diamond, crosses a line.

How hard is each stone, really?

Here is where the daily-wear question gets answered. Jewelers measure scratch resistance on the Mohs hardness scale, which runs from 1 (talc) to 10 (diamond). The scale is not linear, so the gap between a 6 and an 8 is bigger than it looks. Just as important is toughness — resistance to chipping and breaking — which is a separate property. A stone can be reasonably hard and still be fragile if it has cleavage, meaning a built-in plane along which it splits cleanly. The numbers below come from the International Gem Society.

Stone	Mohs hardness	The catch	Everyday wear
Turquoise	5 to 6	Soft and porous; absorbs oils, sweat and lotions, which can discolor it over time	Gentle wear; keep it out of rings that take knocks
Tanzanite	6 to 7	Has perfect cleavage; a sharp knock at the wrong angle can chip or split it	Better as earrings or a pendant than a daily ring
Zircon	6.5 to 7.5	The hardest of the three, but brittle — facet edges can abrade with rough wear	The most wearable, with a little care
Blue topaz	8	Hard, but has perfect basal cleavage; color is almost always from treatment	Durable if protected from sharp blows

Read the table by the middle column, not the first. Turquoise is porous, so it drinks up whatever it touches and can dull or shift color. Tanzanite looks fine on paper, but its cleavage means one hard bump can chip it, which is why jewelers point people toward tanzanite earrings and pendants over rings. Zircon is the sturdiest everyday pick, though its facet edges soften over years of rough wear. And blue topaz looks like the winner at Mohs 8 until you notice its cleavage — struck the wrong way, it can split despite being hard. The honest takeaway: none of these is a set-and-forget stone the way a sapphire or a ruby is. They are beautiful, they are affordable, and they all reward a little thought about where you set them and how you wear them.

What you will actually find in stores

Two things trip people up at the counter, and both come down to treatment. The first is that most turquoise on the market is not raw, natural stone. A large share is stabilized — treated with resin to harden it and hold its color — and some "turquoise" is not turquoise at all, but dyed howlite, a cheaper white mineral colored to look the part. Neither is a scandal when it is disclosed, but you deserve to know which you are buying, and stabilized turquoise should cost less than untreated stone.

The second is blue topaz. You will see it sold as a December birthstone constantly, because it is the durable, easy-to-source stone many affordable birthstone pieces quietly use. Its saturated blue is almost always created by irradiating and heating colorless topaz — natural blue topaz is rare and usually very pale. So blue topaz is a genuine, common commercial substitute for December, just not part of the official three, and its color is a treatment rather than nature.

Choosing a December piece you can actually wear every day

If a birthstone piece is going to be a gift someone puts on and forgets about, the stone's softness matters more than its sparkle. Here is how I think about it.

• Match the stone to the placement. Rings take the most abuse, so save your softer stones — turquoise, tanzanite — for earrings, pendants and pieces that hang rather than get bumped. If it has to be a ring, choose zircon or a well-protected setting.
• Let the setting do the protecting. A bezel setting, which wraps metal around the girdle of the stone, shields a cleavage-prone gem like tanzanite far better than tall prongs that leave it exposed.
• Be realistic about "waterproof." A porous stone like turquoise is never truly waterproof, no matter what the metal around it is. If the goal is a piece that survives showers, workouts and the pool without a second thought, that is a job for the metal and a hard or well-set stone, not a soft one.

This is exactly the gap our own pieces are built to fill. Stylr jewelry is made on 18k gold-plated 316L stainless steel — plated, to be clear, not solid gold, and low-nickel rather than nickel-free, since the steel locks its small nickel content into the alloy and releases very little. It is chosen so a piece holds up to daily life instead of asking you to baby it. If you would rather have something you can genuinely leave on, browse our waterproof jewelry and let the metal carry the everyday wear.

How to care for each December stone

• Turquoise: keep it dry and away from cosmetics, perfume and household chemicals. Wipe it with a soft, slightly damp cloth — never soak it, and never put it in an ultrasonic cleaner.
• Tanzanite: clean it with warm, soapy water and a soft brush. Skip ultrasonic and steam cleaners entirely; both the cleavage and sudden temperature changes can crack it.
• Zircon: the toughest of the three, but store it separately so harder stones do not scratch it and its facet edges stay crisp. Warm soapy water is fine; avoid steam and harsh knocks.

Frequently asked questions

What is the December birthstone?

December has three official birthstones: turquoise, zircon and tanzanite. Turquoise is the traditional choice, zircon was added in 1952, and tanzanite in 2002. Blue topaz is a common commercial substitute but is not on the official U.S. list.

Is zircon the same as cubic zirconia?

No. Zircon is a natural mineral, zirconium silicate, that forms in rock. Cubic zirconia is a lab-made diamond simulant, zirconium oxide, with a similar-sounding name but a completely different material and origin.

Which December birthstone is most durable for everyday wear?

Zircon is the hardest at about 6.5 to 7.5 on the Mohs scale, though its facet edges can abrade. Tanzanite (6 to 7) has cleavage that can chip, and turquoise (5 to 6) is soft and porous. None is as tough as sapphire, so protect them in wear.

Is store-bought turquoise real or treated?

Much of the turquoise sold today is stabilized with resin, and some pieces labeled turquoise are actually dyed howlite. Both are common and legitimate when disclosed, but they should cost less than untreated natural turquoise, so ask the seller which you are buying.

Can I wear a December birthstone ring every day?

You can, with care and a protective setting such as a bezel. But for a piece you truly never take off, a soft porous stone is a fussy choice; a tarnish-free steel piece is far more forgiving of showers, sweat and daily knocks.

December's stones are proof that "harder" and "tougher" are not the same word, and that the prettiest option is not always the one you can wear the hardest. Choose the stone for where it will live on the body, protect it with the right setting, and it will last. For more on the traditional favorite, see our guides on what turquoise jewelry actually is and how to care for turquoise jewelry. And if you would rather skip the fuss entirely, our waterproof jewelry is built to stay on.

If you want to wear December’s stone rather than read about it, our Personalized Cross & Birthstone Necklace is made in a December version — 18k gold plating over a 316L stainless steel base, built for daily wear. The stones are cubic zirconia, not mined gems, and the product page says so.