Tag Archives: birthstone

When I was younger I was always annoyed that everything October was pink. October’s birthstones are opal and tourmaline. Opal being a pricey stone and not super cheap even in lab grown options, pink rhinestones were the way to go in key chains, toy rings, and other such birthday/astrologically themed trinkets.

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The Autumn side of August

The green gemstone peridot is the most popular birthstone for August, but it has another, less gemmy birthstone, sardonyx. It seems fitting that one of August’s stones is all sparkle and leaf green, while the other is duller and browner and edging into fall.

 sardonyx

Sardonyx is a type of onyx that can be found in shades of browns and reds as mixed with black or white. It’s more common than black onyx (which is naturally bands of black and white-not solid), but since black onyx is a higher demand stone, sardonyx is often dyed black. The sard prefix probably comes from a Persian root for yellowish red. Its colors form very even and straight bands.

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Royal Purple

Amethyst from Erte’s Precious Gems Suite

Amethyst is the traditional birthstone for the month of February.

 

(I remember being jealous as a kid, since there were purple stones for February but October always got something pink instead of opal or even fake opal!)

 

Iron impurities in quartz give amethyst its wonderful purples-from pale lilac to royal.

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A gem for all seasons

A somewhat belated note on the June birthstone you’re least likely to casually come across.

 

It’s an unusual and pretty rare stone called Alexandrite. Alexandrite is a variety of chrysoberyl, a more common form of chrysoberyl is cat’s eye.

The more common, though still striking, cat’s eye chrysoberyl.

 

Chrysoberyl are oxide minerals and despite the name, bear no relation to beryl gemstones like aquamarine and emerald.

 

What’s amazing is that alexandrite changes color depending on the type of lighting it is viewed in. This happens when chromium atoms replace some of the aluminum atoms in the chrysoberyl structure.

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Regal Greens

4th century gold Tunisian necklace in emerald, sapphire and pearl.

Emerald is May’s traditional birthstone, but since good quality emerald is getting harder to find (I still say the most beautiful ones I ever saw were at the British museum in ancient jewelry) it seemed a good month to look at two other gorgeous green gems.

 

Especially since outside the spring greens are starting to ripen!

 

Chrome diopside

Chrome diopside really needs a trade name. Despite the fact that it sounds like a polishing agent, it is a beautiful green stone that is sometimes used as an emerald replacement.

 

The word diopside comes from Greek, meaning double shape, after the shape of its crystals. Chromium is the element that gives chrome diopside its name and color. Traces of chromium are also what make emeralds green. Oddly enough, it’s also what makes rubies red!

 

Chrome diopside rough

Chrome diopside can indicate proximity to diamond mines. So some people search for minute crystals as a hint of where to mine. Most chrome diopside come from Siberia, near the diamond mines there. It is also sometimes found near the diamond mines of South Africa.

 

It is a much softer stone than emerald. The hardness of stones is measured on the Mohs scale, and chrome diopside sits around 5.5-6.5. That means it is more easily scratched than emerald. It is best used in earrings and pendants; or in rings with a protective setting.

 

Emerald with jardain

Emeralds are tougher. They are rated at 7.5-8 in the Mohs scale; but it is one of the few gemstones expected to have inclusions. Inclusions break up the crystal structure and make both visible and structural flaws.

 

(One of the things I love about emeralds is that even the best gems are expected to have flaws. Visible flaws in emeralds are called jardain, French for garden, for the foliage effect flaws add to the stone.)

 

Green tourmaline showing some of the color variations to wonderful effect. Faceted by Robert Schock.

Tourmaline sits between these two on the Mohs scale at 7-7.5. The name tourmaline covers a large group of related stone species that come in all different colors: clear, yellow, pink, red, brown, green, violet and black. Multicolored crystals are more common than single colored ones.

 

Tourmaline crystal

Originally a lot of the different stones each had their own name; For instance verdelite was the name given to all shades of green and indicolite for all shades of blue tourmaline. Now they’re mostly just referred to as green tourmaline or blue, etc.

 

One of the classic color combinations for tourmaline is the watermelon tourmaline: a crystal that’s green on the outside and shades to pink on the inside, so that the cross-section looks like a slice of melon. (I don’t actually like watermelon, but I’ll take a slice of watermelon tourmaline any time, thank you.)

 

The floral carving is an interesting twist on the watermelon slice tourmaline.

The intense pink and green are normally the most desired tourmaline variants. The pinks range into the most delicious raspberry colors while the best greens can almost put emeralds to shame.

 

Tourmaline is found in many places all over the world. Brazil is the largest supplier, but mines are found on every continent except Antarctica. In the United States tourmaline is found in Maine and California, and is the former’s state stone.

 

I mixed chrome diopside and green tourmaline for an emerald effect in this summer green tree of life pendant.

I mixed chrome diopside and green tourmaline for an emerald effect in this summer green tree of life pendant.

* Care and feeding of chrome diopside- it’s light stable, so it won’t fade in sunlight like some other gems (yes, even natural ones) however, it is sensitive to heat and hydrofluoric acid, so pieces with chrome diopside shouldn’t be cleaned using a steam or ultrasonic cleaner

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Diamond and Verse

The idea of birthstones seems to go pretty far back but I’ve yet to find much trustworthy information on the whys and wherefores. In 1870 Tiffany & Co. published a poem with the traditional birthstones of English speaking countries, which sort of codified them. As new gemstones are discovered the calendar is sometimes modified to include them. (For instance adding pink tourmaline to October-why couldn’t they have left well enough alone? And tanzanite to December-now that’s an upgrade!)

 

April has remained steadfastly diamond.

 

“She who from April dates her years,

Diamonds shall wear, lest bitter tears

For vain repentance flow; this stone,

Emblem of innocence, is known.”

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Turkish Blue

Tree of turquoise chips with sterling silver and copper.

Tree of turquoise chips with sterling silver and copper.

Turquoise is one of December’s traditional birthstones. (As designated by the American Gem Society. The other two are zircon and tanzanite.)

 

To me it’s such a summery color. I guess on the right winter day you can have a turquoise sky brilliant against the snow and bare trees.

 

Turquoise supposedly gets its name from the middle French for Turkey, since the trade routes that first brought turquoise to Europe came through that country.

 

It’s an opaque stone with a texture somewhere between waxy and glassy. It takes polishing well but is relatively soft. (Mohs 5-6) The color can change with exposure to cosmetics, oil, sweat and detergents as well as bright light. Turquoise seems to be another of those stones that is popular for rings but probably shouldn’t be used for them! At least take them off before washing your hands.

 

Turquoise is a secondary mineral; it forms when acid solutions leech elements from other minerals. It doesn’t have a crystal shape, so tends to form clusters or nodules in veins and often grows with other copper related minerals. (For example, chrysocolla or malachite. Great color combinations.) The blue in turquoise comes from the copper, and the green hints from iron and chromium.

 

Turquoise is one of the most ancient gemstones; it has been mined for at least 5000 years. The mines in the Sinai were already worked out by 2000 BCE! (And people have been making imitations almost as long. The Egyptians had faience, a type of pottery glazed in a turquoise color.)

 

In the states we tend to associate turquoise with the Southwest. In a lot of places it’s a lucrative secondary to copper mining. Apparently the classic Southwestern silver and turquoise jewelry is a fairly modern phenomenon. Supposedly the concept was pushed by traders in the 1880s. Before then Native Americans used turquoise in solid beads, mosaics and carving rather than settings.

 

Some of the turquoise minded in the southwest is still gem quality (especially the Sleeping Beauty and Kingman mines), but a lot of it is treated to get it stable enough to use.

 

It’s kind of frustrating, because it is hard to tell if material sold has been dyed or stabilized with plastics or epoxy. On the plus side, it has also led more recently to a type of stabilizing/reconstituting that adds brass or copper veining through the stone. It doesn’t make any pretense at being natural and is a lot of fun to work with!

 

The best imitation is called Gilson turquoise. It has both uniform color and veined variants. The most common way to fake turquoise is to dye naturally white stones that possess similar textures (and veining patterns).

 

Value for turquoise seems to be very much in the eye of the beholder. Some hold out for the most turquoise of the turquoises with very uniform color-the best quality of this type comes from Iran and is the most desirable in the middle east and much western jewelry.

 

Others prefer the stone to have a cob webbing of matrix when the pattern and color is complimentary, emphasizing the richness of the color. This is the type generally preferred by artists in the Far East as well as by many Southwestern artists.

 

Oh, and apparently there’s a Turquoise Museum in Albuquerque, NM. Who Knew?

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