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The December birthstone

Learn more about turquoise, tanzanite, and blue zircon: the birthstones for December

© | Dreamstime

The idea of a different gemstone representing each month of the year dates back to Biblical times. The Jewish historian Josephus made a record of Aaron from the Book of Exodus wearing a breastplate decorated by twelve stones all the way back in the first century. We will be exploring the properties and traditions of each stone monthly on Facet. In December, the American Gem Society recognizes three birthstones: turquoise, tanzanite, and blue zircon, three stones best known for their beautiful shades of blue.

Curious about the stones that represent other months?

Peridots and sardonyx represent August: Check it out here

Sapphires for September: they ward off evil!

The kaleidoscopic stone for October is the opal 

Topaz and citrine: the golden gems of November
©Kia Resnick
Turquoise has been a beloved stone for millennia, with examples dating to 3000 BCE having been found in ancient Egyptian tombs. Originally mined in Egypt’s Sinai Peninsula, most of today’s turquoise is found in the American southwest, specifically Arizona, Nevada, New Mexico, California, and Colorado.

Turquoise ranges in color from sky blue to greenish and sometimes contains veins of its host rock, called matrix. The presence of matrix usually diminishes the value of the stone but some designers prefer it. Turquoise is a relatively soft stone, ranging from a crumbly 2 on the Mohs scale or hardness up to about a 6, which explains why it is a popular stone used for carving. Because of its softness, turquoise is often treated to enhance durability, though some treatments like reconstituting it or impregnating it with resin are controversial.

Turquoise is said to grant protection and promote happiness.
© | Dreamstime
Tanzanite is named for its place of origin (Tanzania, near Mount Kilimanjaro), where it was discovered in 1967. It measures a 6.5 to 7 on the Mohs scale of hardness. While it has to be carefully cut (and usually heat treated) to bring out its deep blue color (which often has violet overtones) and minimize the undesirable brown hues, it is often used as a substitute for the much costlier sapphire. Because it is much softer than sapphire, though, it is better used in earrings or other settings where it won’t be subject to a lot of abrasion. 
© | Dreamstime

Not to be confused with cubic zirconia, zircon is a spectacular gemstone that comes in a wide array of colors, though usually it is brownish-red naturally. Heat treatment changes zircon to its popular colorless (and thus a substitute for diamond, called Matura Diamond), gold, or blue varieties, blue being the most popular. Measuring 7.5 on the Mohs scale of hardness, it is primarily mined in Australia, though other sources include Thailland, Sri Lanka, Tanzania, Cambodia, Canada, and the United States. Zircon is believed to induce sleep, ward off evil, and promote prosperity.

Facet has lots of projects that can help you incorporate turquoise and other shades of blue into your wardrobe. Here are just a few:


Try turquoise two ways for a classic set that suits any season.


String and knot an eight-strand necklace with turquoise drops for a casual, yet elegant look.



Enclose turquoise ovals within vintage-inspired stitched bezels.

All you wireworkers will love to capture a beautiful stone donut with a basketweave bail.




For the look of tanzanite without the expense, try a Swarovski crystal-embedded bead on a bracelet of WireLace.