Tag Archives: gemstones

Book Review: Stoned by Aja Raden

For the most part I really enjoyed this book. It’s a fun read with some excellent lines.* y648


I appreciate her efforts to clearly explain things as vastly different as the geological and biological processes that create gemstones and pearls, and different concepts of value to the psychology of want and envy and their roles both in marketing and the shaping of the political world.

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Amber Golden and Ambergris

Carved Amber Dinosaur HatchlingWith Jurassic World inspiring visions of mosquito embedded amber and #cephalopodweek on Science Friday it seemed like a good time to take a look at amber. (It connects, really, at least in my head…)

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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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September Shades

I realized that I haven’t geeked out over the gemology of birthstones in a while. So a slightly late visit to September’s traditional birthstone, sapphire.

Sapphires are a gemstone variant of corundum. Red gemstone corundums are known as rubies, every other color is categorized as sapphire. (Despite the very name coming from a Greek word for blue.)

For a long time the word sapphire was applied to different stones. Even into the Middle Ages a reference to sapphire was probably to what we now call lapis lazuli.

Corundums are composed of an aluminum oxide, the bond between the aluminum and the oxygen atoms are short and the atoms are nestled tightly together. This makes them comparatively dense despite being made of light elements, and it makes them durable. As mentioned with rubies, corundum is second only to diamond for hardness. The majority of corundum found is used for industrial purposes.

Because of its sturdiness corundum lasts long after other sediments wear away. Since it is dense, it tends to be found in placer deposits (where erosion and gravity have essentially sifted the heavier bits and pieces together into a gravel over the millennia) and alluvial deposits (where water washed away the original sediment).

For traditional blue sapphires, value is determined by the color of the stones-how pure, how vivid, and how dark. Generally color wise the bluer the better. The blue color comes from traces of titanium and iron.

Monatana’s Yogo sapphires come in a wide range of colors.


A small amount of purple secondary hue is considered acceptable, and if subtle enough, can even raise the value of the gem. Vanadium is the coloring element that brings purple and violet (and orange!). Any trace of green (a smaller iron content) lowers it vastly. (I don’t know why, sounds like it’d be a lovely color to me!) Likewise, the richer and more saturated the color the better.

Depending on who you ask the most preferred shades are either an almost primary blue or a slightly lighter rare cornflower blue found in a small part of the Himalayas.

Recently a pink-orange sapphire variant known as padparadschah (chromium and vanadium) sapphire has gotten very popular.

Traditionally sapphire has symbolized loyalty, faithfulness, sincerity and truth. The richness of its color keeps it associated with nobility and royalty. And despite its myriad of shades, it is first and foremost the blue to which every other gem is compared.

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O is for October and Opal

Precious opal is October’s traditional birthstone.


It’s one of my favorite stones, at least to admire if not to work with. Opal is similar to the feldspars in that it has the addictive quality of each gem being different. Boulder opals, trails and pools of opal still in their matrix stone, have a wonderful narrative feel. Like gazing at clouds they have shapes and stories and weather in them.


Opal under a microscope.

Their chemical composition is hydrous silicon dioxide. The stunning colors come from the fact that opal is composed of tiny spheres layered in essentially a silica jelly. The light passing through and refracting off of them is what gives them that fire. How even the spheres and how close together changes the intensity and color.


Opals are between 3% and 30% water. The color can diminish if the opal loses some of its water through heat or cracking. Keeping them in or near slightly moistened cotton wool can prevent drying out over time. Sometimes the play of light in old opals can be partially resuscitated with oil or epoxy resin.


Couldn’t get a decent photo of the ring I’m trying to salvage, so a boulder opal I wrapped with amethyst instead 🙂

(I’m trying to use oil treatments to save the opal from an old beaten up poison ring. But it was a poison ring, with my birthstone, I had to try it!)


Some attribute the stories about opal being a cursed gem to the fact that special care needs to be taken when working with it. It’s a soft stone, so sensitive to knocks as well as to heat, acids and alkalis.


(I can sympathize with this, I got some Ethiopian opal wet and that was the end of that…I’ve never had trouble with any other sort, but then wire wrapping doesn’t tempt fate too much in terms of either heat or pressure.)


The same is true of wearing them. They’re stunning and not particularly high maintenance, but rings especially are susceptible to being knocked about and dried with or abraded by harsh soaps. So part of the bad luck bad rap may be also be that heirloom quality rings don’t seem to last as long as other gems unless they’re well taken care of over the years!

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(Un)earthly Color

I fell for jacaranda trees when I saw them live for the first time this Spring. They belong in more tropical climes then I do, so I’d only seen them in pictures.


I’d been told in the past that my amethyst tree looked like a jacaranda, but when I saw them in person I though they looked carved from tanzanite. (And thus upon my return the hunt for appropriate gems!) I stumbled on this lovely poem when I was looking up the jacaranda for color checks:



A Jacaranda Tree

Ann Beard


 A Jacaranda tree stands tall, and sways as if to say,

Look! At this magnificence, I’m wearing blue today.

forgive the way I shout aloud, my lack of modesty,

but nowhere in this troubled world is finery like me.


Light rays slide between each leaf, to settle on the tips

to lightly kiss your face with a hundred million tiny lips.

You only have to lift your eyes to greet the filtered sun

a sight I guarantee will warm the heart of everyone.


Though very tall, my leaf is small, its form is one of fern,

large panicles of bluebells swell to trumpet unconcern.

A Bee collecting nectar from an ample deep white throat,

takes flight to join its family, and of its feast to gloat.


Look up to see each fern like leaf, floating up on high,

like footprints of a centipede that stroll across the sky

See how far my branches reach, admire their greenery,

so beautiful and strong, I am the Jacaranda tree.


When I got home I started puttering with colors to make a jacaranda tree pendant. Alone the tanzanite looked a little too cold, so I mixed in amethyst for warmth, added labradorite for a flash of blue and peridot for a hint of greenery. I think the tanzanite still firmly holds center stage though!


Tanzanite is a rare blue/purple/violet gem only found in Tanzania. (Generally it looks more sapphire blue in natural light and more purple in artificial light.) It’s actually much rarer than diamond.


Tanzanite is a blue form of zoisite. In 1967 miners discovered some beautiful translucent violet stones while mining for graphite. It gained its trade name of Tanzanite from a marketing campaign by Tiffany & Co. They wanted to emphasize its rarity didn’t think it would sell under the name blue zoisite.

After the first bout of blue stones the trail ran out. All miners found were russet and khaki colored zoisites. They sent samples for study to the same German company that had handled the original gems. The samples were tested, and it was discovered that heating those brown stones to over 700 degrees got rid of the browns and yellows and turned them into the striking blues.


At this point it is pretty much assumed that any tanzanite on the market has been heat treated. Since this is a known practice, it isn’t considered a cheat.


(When trying to figure out the best colors to describe the stone I was looking color names up online. I think of violet as purple towards the blue end of the spectrum, which it is…but apparently web violet is a from of magenta. Who knew? And who knows why? Why not just call it pale magenta?)

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Brecciated Backgrounds

A bit of a bookend for Chatoyant Skies and its ode to Blue Pietersite and El Greco…

The more sharply delineated golden pietersite with its iron oxide shimmers sometimes reminds me of the backgrounds in Gustav Klimt’s paintings.

Klimt was an Austrian symbolist painter. The son of a jeweler, he was born and studied near Vienna and became a successful muralist. In the early 1890s his father and brother both died and Klimt became the head of both families. This newfound responsibility is believed to be part of what caused the significant change in his personal style.

One piece I saw and really liked (and didn’t realize it was his right away) is Two Girls with Oleander. It isn’t as planar, or hammering death and the erotic as his usual work. (Though it is two pretty girls admiring a poisonous plant…) It’s an almost gentle piece. The painting is dated to 1892, so I wonder if it’s before his new style fully took over.

After the turn of the century he entered his Golden phase, where he incorporated gold leaf into the increasingly flat plane of his paintings. (It was these that pietersite sometimes brings to mind.)

His most famous piece, The Kiss, is from this period. It is probably on as many totes, mouse pads, umbrellas, dorm room posters and ‘what-have-you’s as Monet’s water lilies.

Klimt is generally not my style. I can appreciate the work and the impact, but unlike in Egyptian art, for some reason the flatness doesn’t really appeal to me. Or perhaps it’s the way the figures have to fight the background to escape.


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