December Birthstone Guide: Turquoise, Tanzanite and Zircon

Someone in your life has a birthday in December, and you have been told it is "turquoise". Then a friend says tanzanite, and a jeweller's website says zircon. Nobody is wrong. The December birthstone is one of the few that comes as a set of three, and each stone looks, wears and costs very differently.

Short answer: The December birthstone is turquoise, tanzanite or zircon. Turquoise and zircon are the traditional stones, and tanzanite was added in 2002. Turquoise ranges from opaque sky blue to green, tanzanite ranges from blue to violet, and zircon comes in many colours, most often blue. For daily wear in a ring, zircon is the toughest of the three.

At  Manna Jewellers in Birmingham's Jewellery Quarter, we hand-finish every ring in our workshop. We don't currently have ready-made December stone rings, but you can browse our  gemstone rings collection and ask us about sourcing a December birthstone or making a piece to order.

Quick takeaways

• The December birthstone has three options: turquoise, tanzanite and zircon.

• Turquoise and zircon are the traditional December birthstones. Tanzanite was added in 2002.

• Turquoise rates about 5 to 6 on the Mohs scale, tanzanite 6 to 7 and zircon 6 to 7.5.

• Zircon is a natural gemstone. Cubic zirconia is a different, lab-made material.

• Tanzanite and turquoise suit earrings and pendants best. Zircon is the better choice for an everyday ring.

• Most tanzanite is heat-treated, and turquoise is often stabilised or dyed, so ask what has been done to a stone before you buy.

December birthstones compared

The hardness ranges and care notes come from the Gemological Institute of America's  December birthstone guide.

Which stones are December birthstones?

Turquoise and zircon were the traditional choices for December for a long time. Tanzanite arrived much later. The American Gem Trade Association announced on 30 October 2002 that tanzanite would join the December birthstone list, with Jewellers of America, the American Gem Society, the Gemological Institute of America and the International Colored Stone Association agreeing to it, as  JCK reported. That is why you see three December birthstones on most lists today.

Having three December birthstones means you can choose by colour, budget or how you plan to wear the piece. Our  birthstones by month guide sets December beside the other eleven months.

Turquoise: the December birthstone with the longest history

Turquoise ranges from grass green to a bright sky blue. The most prized shade is robin's-egg or sky blue, which the trade often calls Persian blue after the stone's long link with Iran, according to the Gemological Institute of America'sturquoise guide. Many pieces show dark veins of the rock the stone grew in, and some people prefer those markings to a plain colour.

Turquoise is the softest December birthstone, at about 5 to 6 on the Mohs scale. It does not like heat, acids, cosmetics, or skin oils, and much turquoise on the market has been stabilised with resin or dyed to improve its colour and hardness. That does not make it a poor stone, but it does mean you should ask. For a ring you wear often, or a pendant that sits away from knocks, turquoise works well.

Tanzanite: the newest December birthstone

This December birthstone comes from one place on Earth. The Gemological Institute of America says the Merelani Hills in Tanzania are the only commercial source, and the gem takes its name from the country, according to itstanzanite guide. People first found blue-to-violet crystals there in the 1960s.

Its colour draws people to this December birthstone. Tanzanite shows different shades depending on the direction you look at it, so that a cut stone can flicker between blue, violet, and a hint of grey-green. Most tanzanite is heat-treated to bring out the blue and violet, and the same guide notes that this treatment reduces the brownish and greenish tones.

At 6 to 7 on the Mohs scale, tanzanite scratches more easily than sapphire and can crack with a hard knock or a sudden temperature change. The Gemological Institute of America suggests earrings and pendants over everyday rings. If you want a tanzanite ring, pick a low, protective setting and take it off for heavy work. Our guide to  engagement ring settings explains which settings best protect a stone.

Zircon: the sparkly and often misunderstood December birthstone

Zircon is a natural gemstone and one of the oldest minerals on Earth. It comes in yellow, green, red, reddish brown and blue, and colourless zircon is also common, according to the Gemological Institute of America's  zircon guide. The blue stones sold as December birthstones are usually heat-treated to reach that colour. Colourless zircon has strong brilliance and fire, which is why people mistook it for diamond for centuries.

At 6 to 7.5 on the Mohs scale, zircon is the hardest of the three December birthstones, though it abrades easily, so a protective setting still helps. It is also the one most likely to be confused with something else.

Zircon vs cubic zirconia

Zircon and cubic zirconia sound similar but are different. Zircon is a natural gem mined from the ground. Cubic zirconia is a lab-made stone sold as a diamond alternative. If a listing says "zircon" and you are not sure which it means, ask for the stone to be named in full, and check the hallmark and any stone report for the details.

Which December birthstone should you choose?

The right December birthstone depends less on the birthday and more on the wearer. Use this as a starting point.

If you are not sure which December birthstone to pick, decide on how you will wear the piece. A ring takes more knocks than a pendant, so a harder stone and a protective setting matter more there. Our  birthstone pendant guide covers choosing a pendant, and our  gemstone ring anniversary guide helps if the gift is for a milestone.

What colour is the December birthstone?

The December birthstone colour is blue in most cases, though not always the same blue. Turquoise ranges from sky blue to green, tanzanite ranges from blue to violet, and zircon is most often a clear, bright blue. If someone asks you for "the December birthstone colour", blue or blue-green is the safe answer. You can see how the colour fits into the other months in our  November birthstone guide, which covers the stones that come right before December.

Some retailers also sell blue topaz as a December birthstone. It isn't one of the three official December birthstones, but it is a hard, affordable blue gem many people choose instead.

How to look after December birthstone jewellery

Every December birthstone needs gentle handling, and the care points are similar. Whichever December birthstone you pick, these habits help.

• Clean them with warm water, mild soap and a soft brush. The Gemological Institute of America advises against steam and ultrasonic cleaners for all three.

• Keep turquoise away from perfume, hairspray, cleaning products and sweat, which can dull or discolour it.

• Protect tanzanite from knocks and sudden temperature changes.

• Keep zircon out of strong light and heat for long periods, because some treated stones can fade.

• Store each piece separately so harder stones don't scratch softer ones.

If a ring needs work after years of wear, our  jewelleryrepair service can re-set or tighten a stone.

Expert tip: When a stone is described only by its colour, ask what it really is and whether it has been treated. The Birmingham Assay Office offers gemstone reports that identify a stone and say whether it is natural or synthetic, with tanzanite graded for colour and clarity, and its intermediate level adds treatment analysis, according to its  gemstone reports page. Bring any December stone you own to our Jewellery Quarter workshop, and we will tell you what we can see first. If you want a piece made around your December birthstone, start with our  bespoke jewellery service, and  book an appointment to talk it through.

FAQs

What is the December birthstone?

The December birthstone is turquoise, tanzanite or zircon. Turquoise and zircon are the traditional stones, and tanzanite was added in 2002.

What colour is the December birthstone?

Mostly blue. Turquoise runs from sky blue to green, tanzanite from blue to violet, and zircon is most often a bright blue, though it also comes in other colours.

Is tanzanite a real December birthstone?

Yes. The American Gem Trade Association announced it as a December birthstone on 30 October 2002, with other major gem and jewellery bodies agreeing, according to JCK.

Is zircon the same as cubic zirconia?

No. Zircon is a natural gemstone. Cubic zirconia is a lab-made stone sold as a diamond alternative. They are different materials with different properties.

Which December birthstone is best for a ring?

Zircon is the hardest December birthstone, at 6 to 7.5 on the Mohs scale, so it is the best fit for a ring worn daily. Tanzanite and turquoise are softer and suit earrings and pendants better, or a ring worn with care.

Related articles

• Birthstones by Month: The Perfect Birthstone Ring for Every Month: Every month's stones in one place.

• November Birthstone: Topaz and Citrine: The stones that come right before December.

• Birthstone Pendant Necklaces: Meaning and How to Choose: Choosing a pendant for a December birthday.