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.
Tag Archives: birthstone
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 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.
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.
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.
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.
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 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 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.
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.)
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.
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 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.
* 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
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.”
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.
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.
(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!
I love so many different types of stones that choosing a single favorite would be like choosing a favorite dessert-totally impossible. Sometimes you want chocolate, others ice cream, or perhaps it’s fresh fruit you’re craving…
It’s a type of feldspar, like labradorite (another favorite of mine). Feldspars are a family of silicates that make up about 60% of the earth’s crust. Large parts of the moon’s crust are composed of feldspars too.
Moonstone has a beautiful shimmer-called adularia-the traditional color is blue, and the nearly clear moonstone with that ghostly rich blue is especially highly valued. There is also grey moonstone and peach-both have a soft white shimmer, and rainbow, which normally is a white or white/clear base with many different colors. The colors come about because the stone’s structure is layered, and those layers refract light at different angles. (Like a built-in faceting system!)
I like working with rainbow moonstone because of the gorgeous range of colors. The whole rainbow really will appear in some pieces. I also like the fact that each stone will have its own unique pattern of shimmer and color play.
It is a comparatively soft stone. It has a Mohs hardness of 6, which makes it softer than quartz or garnet (though harder than opal) and more easily scratched. I try to avoid the temptation of moonstone rings, since those take the most knocks.
(Title from Cat Steven’s Moonstone.)
Amethyst is a popular stone, one of very few naturally occurring fully purple gems. It is the traditional birthstone for February. Amethyst is a variant of quartz. Iron impurities give it those beautiful shades of purple. Regarding its famous color-if you run across prasiolite, sometimes called green amethyst, just be aware that it’s most likely heat treated or irradiated. (It’s not an issue, so long as you know and aren’t being told or charged for the natural gem. They are a lovely mint green, it’s just that the natural stone is extremely rare.)
Geodes are partially filled hollow cavities in rock that are lined by minerals. Their name comes from the Greek for earthlike. (As in Gaia.)
One example of a geode would be a gas bubble in lava. That hollow stays and over time solutions containing dissolved minerals can filter in and leave deposits within the hollow, often resulting in layers of agate and then layers of quartz and/or calcite crystals.
Studying the order of the layers can give a window into the geologic history of the area in which the geode is found.
I like working with slices of geodes because you get to see that external skin and the swirls of agate layers as well as the sparkling crystals.