Ruby – the birthstone of July


We’re halfway through the year folks, when did that even happen?! The first half has been so much fun but it’s been speeding by for me and I feel like it really needs to slow down. So much to do / see / enjoy and so little time.

Anyway, let’s steer the focus back to the birthstone for this very summery month – the ruby. You July babes sure are lucky to have this fabulous gemstone as your birthstone!

July birthstone jewellery set with genuine feminine pink rubies and 14k gold fill chains and earwires. Made by Linda Sääv Jewellery.
Ruby jewellery set, the perfect set for a July born babe who likes a touch of feminine pink. All pieces made by Linda Sääv.

The feminine ruby

Rubies for me are the embodiment of femininity in a gemstone. Their hot pink to blood red colour is divine and are loved by women of all ages. Even someone who might not be that in to pink will still get intrigued by a ruby.

I mean if your jaw doesn’t drop from the sight of the ruby pictured below, you need to get your eyes checked!

Hot pink ruby wire wrapped in 14k rose gold fill, dainty and delicate jewellery at its best. Made by Linda Sääv Jewellery.
Hot pink and glowing little ruby wrapped in flattering 14k rose gold fill wire. Made by Linda Sääv.

Ruby science

The ruby is a pink to red variety of the mineral corundum (aluminium oxide, Al2O3) and is a sibling to the other corundum colour varieties named sapphires. In fact, all other gem-quality corundum stones not having a shade of pink or red is called sapphires (read on for the pink sapphire versus ruby debate).

A completely pure corundum is colourless, so rubies get their colour from trace amounts of chromium in the crystal lattice. The more chromium, the stronger the red colour. The chromium can also cause fluorescence, which adds to the glow and intensity of the red colour when viewed under ultraviolet light – even from the ultraviolet light in sunlight.

Colourless and Pink Ruby Crystals
Top left: colourless corundum crystal. Bottom left: irregularly shaped glowing pink ruby with a hint of orange. Right: raw ruby, loose and in host rock with a hint of purple. The faceted ruby is more red with a hint of pink.

Iron can also be present in the chemical makeup of a ruby. Iron on the other hand can make the rubies darker and less intense in colour. Higher iron content can also mask the red fluorescence.

50 shades of red

Although rubies are defined to be red, they may exhibit a range of secondary hues, including orange, purple, violet and pink (as already seen in the previous photo). Of the three, purple is preferred because it reinforces the red, making it appear richer. However, too much purple and the ruby moves down the quality scale.

50 shades of red
50 shades of red. Nah, just kidding, sort of. Even though it might not look like it, all rubies are defined to be red in hue. The pink or purple colouration you see is only caused by their secondary hues.

The ruby hex

Rubies (as all corundum varieties) are part of the trigonal crystal system and most often occur naturally as terminated tabular hexagonal prisms. Imagine two stretched six-sided pyramids attached at their base and you have a rough idea of how a ruby crystal looks like.

Natural Hexagonal Ruby Crystals
Top left: raw ruby crystal showing off its hexagonal shape, it’s also showing off that it’s part of the trigonal system with the triangle on its top. Right: a raw ruby with a faint hexagonal shape. Bottom left: a collection of ruby crystals and clusters (and one blue sapphire).

Rubies are naturally very hard with a hardness of 9 on the Mohs scale of mineral hardness. Only moissanite and diamond are harder, with diamond having a hardness of 10 and moissanite falling somewhere in between corundum and diamond.

Naturally imperfect

When it comes to imperfections, all natural rubies have them. Imperfections include colour impurities and inclusions of rutile needles known as “silk”. It’s the rutile inclusions that make distinguishing natural rubies from synthetics or simulants possible.

Rutile Needle Inclusions in Rubies aka Silk
Left: rutile needles (golden) on hematite (metallic). Top right: microscope image of a criss cross pattern made by rutile needles in a ruby. Bottom right: Close up of thin rutile needles making the same but faint criss cross pattern seen above.

The rutile inclusions can sometimes cause an optical phenomenon called asterism. An asterism or “star” is a three-point or six-point surface effect that occur when light is reflected off the structurally oriented rutile needle inclusions of the stone in a certain way. These rubies are usually cut into cabochons to properly display the effect. Similarly, rubies can also show chatoyancy, also called the “cat’s eye” effect. In this case, the rutile needle inclusions are actually increasing the value of the ruby.

Asterism in Rubies Caused by Silk
Two cabochon cut star rubies clearly showing the six-pointed surface effect caused by the silk within.

These days, almost all rubies are treated in some form, with heat treatment being the most common practice. Heat treatment of a ruby improves the colour, removes any purple tinge as well as “silk” which also improves the clarity.

Another treatment is lead glass filling, a treatment where any fractures inside the ruby is filled with lead glass, a treatment that dramatically improves the transparency of the stone.

Untreated versus Treated Rubies
Untreated rough rubies (left) versus heat treated rough rubies (right).

Ruby vs. pink sapphire

The distinction between ruby and pink sapphire is often made by looking at the colour saturation of the stone. If the saturation isn’t high enough it will be called a pink sapphire and subsequently, if the saturation is above a specific threshold it will be called a ruby. Furthermore, one can argue that for a corundum to be called a ruby, red must be the dominant hue.

However, often, the identification of the dominant hue is difficult and can be debated – it’s not clear and it really is just a matter of personal perception.

Historically though, the word ruby referred to shades of red, which technically included pink.

Rubies with same hue but different saturation and tone
Four different corundums having the same hue (red), but showing a variation in saturation and tone. Most gem dealers would classify number 3 and 4 as rubies, whereas number 1 would be classified as a pink sapphire. Number 2 walks the line, it’s a ruby to some, while a pink sapphire to others.

The queen of gems

Ruby is the most valuable variety of the corundum mineral species and rubies can in fact command the highest per-carat price of any coloured gemstone.

The quality of a ruby is determined by the same principles as other precious gemstones: colour, cut, clarity and carat weight – all of which affects its value.

For rubies, colour is the most important quality factor. The finest ruby has a pure, vibrant red to slightly purplish red colour –  called “pigeon’s blood” rubies. After colour follows clarity: a clear stone will naturally be more valuable. However, a ruby without any needle-like rutile inclusions may indicate that the stone has been treated, which lowers its value.

Rubies in the wild

Rubies are most often found in marble. The most renowned rubies, like those from Myanmar, the Himalayas and northern Vietnam, typically form in marble.

Here they’re found in layers that are distributed irregularly within the surrounding marble. The marble is formed from existing limestone deposits during metamorphic (rock-altering) processes.

Marble is a type of rock with low iron content, which means rubies formed in marble are more likely to have an intense red colour due to the lack of iron.

Rubies in Dolomite Matrix
Rubies in marble showing off their more vivid colouration.

Rubies can also be found in basalt rocks. Basalt has high iron content which means that rubies originating in these rocks can have higher iron content as well. And as you’ve already read, the addition of iron can cause the rubies to be darker and less intense in colour (see picture below), as well as mask the red fluorescence, eliminating that extra glow of red colour seen in rubies originating from marbles.

Another type of ruby is found in amphibolite and the most renowned ones originate from Mozambique. These rubies are quite fascinating due to their range in iron content, from as high as rubies found in basalts to as low as rubies found in marbles. This of course causes a wide range of colours for rubies mined in this area.

Rubies in Amphibolite and Ruby Colour Difference Due to Iron Content
Top left: rubies in amphibolite. Right: rubies with high iron content.Bottom left: rubies with low  iron content.

So which ruby is your favourite? The more red ones or the more pink ones? I for one is a sucker for those hot pink fuchsia coloured ones!

. . . . .

I hope this blog post was interesting and fun to read and that you now have a little better understanding and appreciation of this beautiful queen of a gemstone!

I’ll be back in a couple of weeks with something completely different, so until then, have a wonderful time wherever you are!

♥ Linda

Pearls – the Birthstone of June

How can June nearly be over?! It was still snow outside like literally two months ago! We sort of skipped spring here in Sweden and went straight to scorching summer temperatures which was quite a chock for this gal here who isn’t built for such warm weather.

Anyway. June. A month which not only has one but TWO birthstones: moonstone and pearl, and today it will all be about the forever timeless pearl.

Freshwater Pearls June Birthstone Jewellery Set in 14k Gold Fill
Freshwater pearl jewellery set in 14k gold fill.

“Pearls are always appropriate” – Jackie Kennedy

 Pearls are with no doubt the most timeless, classic and sophisticated gem out there. It is regarded as one of the true precious gemstones together with diamonds, rubies, sapphires and emeralds and might even be the best-loved gem of all time.

Simple baroque freshwater pearl pendant paired with a luxurious 14k gold fill chain with elongated links. Handknotted freshwater and baroque pearl necklace using white silk thread and finished with a modern and minimal sterling silver toggle clasp. By Linda Sääv Jewellery.
Top: simple baroque freshwater pearl pendant paired with a luxurious 14k gold fill chain with elongated links. Bottom: handknotted freshwater and baroque pearl necklace using white silk thread and finished with a modern and minimal sterling silver toggle clasp.


Pearls – the beautiful result of a defence mechanism

First things first, what is a pearl?

A pearl is in fact an organic gem that forms inside of a living saltwater or freshwater mollusk.

Pearls are made up of concentric layers of calcium carbonate, CaCO3, either aragonite or a mixture of aragonite and calcite. The layers are held together by an organic horn-like compound called conchiolin. The combination of the two (calcium carbonate + conchiolin) is called nachre –  the stuff that makes up the beautifully iridescent mother-of-pearl.

Aragonite Crystal, Cross Section of a Natural Pearl and Mother of Pearl Shell
Left: the calcium carbonate mineral aragonite, here in crystal form. Top right: natural pearls in cross section clearly showing their concentric rings all the way through to the center of the pearl. Bottom right: the beautiful iridescence of nachre – Mother of Pearl.


The formation of a pearl begins with an irritant inside of the mollusk. The irritant could be organic, a parasite or a tiny speck of sand that found its way inside.

As soon as an irritant settle on the soft tissue it gets enveloped by a pearl sac – a layer of mantle tissue cells which make up the protective membrane on the inside of the mollusk shells. The pearl sac acts as a defence mechanism which seals the irritant off from doing any harm and then nachre is secreted, layer by layer, slowly building up a pearl. Typically, the build-up of a naturally forming pearl takes a couple of years.

Pearl Sacs in Oysters
Pearl sacs that eventually will become full grown pearls.


Perfect shining little spheres of delight

Due to the unique conditions under which natural pearls form they come in a dazzling array of sizes, colours and shapes. Perfectly round ones are actually very rare.

Below I’ve listed some of the most basic shapes:

  • Round
  • Semi-round
  • Button
  • Drop
  • Pear
  • Oval
  • Baroque
  • Circled

Perfectly round pearls are the rarest and most valuable shape. Semi-rounds are often used in necklaces or in pieces where the shape of the pearl can be disguised to look lite it’s a perfectly round pearl. Button pearls are like a slightly flattened round pearl. Drop and pear-shaped pearls are sometimes referred to as teardrop pearls. Baroque pearls are often highly irregular with unique and interesting shapes. Circled pearls are characterized by concentric ridges, or rings, around the body of the pearl.

The Various Shapes of Pearls
The many shapes of pearls. Bottom right from the left: circled, baroque, button, drop and round.


Natural vs. cultured pearls

Natural pearls are nearly 100% calcium carbonate and conchiolin (nachre) grown in concentric layers by mollusks in the wild with no human involvement. Natural pearls are actually incredibly rare, and in the past many hundreds of pearl oysters or mussels had to be gathered and opened, and thus killed, to find even one wild pearl. Their scarcity was the reason for their then extraordinarily high prices.

Today natural pearling is confined mostly to seas off Bahrain and Australia, and to spare any mollusks not carrying pearls all mollusks goes through an X-ray examination in order to reveal any hidden pearls within.

Antique Natural Pearl Necklaces
Left: antique natural pearl and 19ct gold necklace. Right: antique natural pearl necklace with diamond clasp.


Cultured pearls are formed in pearl farms, using human intervention as well as natural processes.

In the pearl farms, a tiny piece of mantle tissue from a donor mollusk is implanted into the recipient mollusk to kickstart the pearl-forming process. To get perfectly round pearls, they often use spherical beads of mother-of-pearl as the nucleus. The use of an implant like this enables cultured pearls to be harvested much faster, just after six months.

Pearl Farming and Harvesting
Top: pearl farming in Fiji. Bottom: pearl extraction process.


Cultured pearls can be distinguished from natural pearls by X-ray examination since their interior gives them away.

Since cultured pearls are often ‘preformed’ they tend to follow the shape of the implant. When a cultured pearl with a bead nucleus is X-rayed, it reveals a different structure to that of a natural pearl. A beaded cultured pearl shows a solid centre with no concentric growth rings, whereas a natural pearl shows concentric growth rings all throughout. Their interior is of course also visible if you cut the pearl in half.

Natural vs Cultured Pearls in Cross Sections
Top: illustration of the difference in interior between a cultured and natural pearl. Bottom left: cultured pearl cut in half clearly lacking concentric rings. Bottom right: natural pearls in cross section with obvious concentric rings all the way to the center.


Pearls, pearls, pearls!

The vast majority of pearls sold today are cultured in pearl farms and comprises mainly of four types: akoya, South Sea, Tahitian and freshwater.


Pinctada fucata (akoya pearl oyster)

  • Introduced to the market in 1916 as the first ever spherical cultured pearl
  • Bead and non-bead cultured
  • Environment: pristine saltwater far from cities
  • Location: Japan and China, larger sized pearls (≥ 8.5 mm) are generally from Japan
  • Colours: white or cream, some with hints of pink or green
  • Size: generally between 3-7mm but can occasionally reach 9-10mm
Akoya Pearls
Top: a classic white pearl necklace made with akoya pearls. Bottom left: akoya pearl in her akoya oyster shell. Bottom right: the subtle overtones of the akoya pearls: silver, rose and cream.


South Sea

Pinctada maxima (silver- or gold-lipped pearl oyster)

  • Culturing began: 1950s
  • Bead and non-bead cultured
  • Environment: saltwater
  • Location: between the northern coast of Australia to the southern coast of Southeast Asia passing the Phillipines as well as Myanmar
  • Colours: silver, white and golden
  • Size: generally between 8-16mm but can very occasionally reach over 20mm
South Sea Pearls
Left: golden South Sea pearls on top of the golden-lipped oyster shell. Right: the golden colour scheme of the South Sea pearl.


Tahitian pearls

Pinctada margaritifera (black-lipped pearl oyster)

  • Culturing began: 1960s
  • Bead and non-bead cultured
  • Environment: tropical saltwater, preferably clean-water lagoons
  • Location: French Polynesia
  • Colours: eggplant purple, peacock green, metallic grey and greyish blue
  • Size: generally between 7-12mm but can very occasionally reach over 16mm
Tahitian Pearls Black Pearls
Top left: baroque Tahitian pearls. Top right: beautiful Tahitian drop pearl pendants made by Malin Ivarsson. Bottom right: the many overtones of Tahitian pearls. Bottom left: a Tahitian pearl in the shell of a black-lipped oyster.


Freshwater pearls

Hyriopsis cumingii or hybrid

  • Appeared on the market in 1971
  • Bead and non-bead cultured
  • Environment: freshwater, usually cultured in lakes and ponds
  • Location: China, Japan and Tennessee, U.S.A.
  • Occur in a wide range of sizes, shapes and colours
Freshwater Pearls
Top and bottom left: the many shapes and colours of freshwater pearls. Bottom right: each freshwater pearl oyster can grow several pearls at once, resulting in a high production and thus cheaper prize.


How to care for your pearls

Pearls are, due to their soft calcium carbonate mineralogy, unfortunately easily scratched. Therefore they need to be handled extra carefully, both when wearing and when storing them, in order to maintain their beauty.

Caring for your pearls by Linda Sääv Jewellery

A first rule of thumb when dressing is: pearls should be the last thing you put on and the first thing you take off. This rule can and should be applied to all kinds of gemstone jewellery to maintain their beauty.

Below is a few pointers to keep in mind for keeping your pearls looking shiny and new to last a lifetime.


  • For routine care, after each wearing, wipe your pearls with a very soft and clean cloth to remove any residues from the skin.
  • For occasional, thorough cleaning, use warm and soapy water . If the pearls are strung, be sure the silk is completely dry before wearing.


  • Store pearls separately from gems and metal jewellery, which may scratch their surface. Instead, store them wrapped in a piece of silk or satin.
  • Never store pearls in a plastic bag. Plastic can emit a chemical that will damage their surface. The same is true of cotton wool.
  • Never store pearls in a well-sealed box for a long time. Like your skin, pearls need a little moisture so they will not dry out.


  • Pearls can be damaged by many chemicals and all acids. The list includes hair spray, perfume, cosmetics and even sweat. Always apply perfume, hair products and perfume before putting on your pearl jewellery. And remember, this can be applied to all gemstone jewellery.

. . . . . . . . . . . . . . . . . . . . . . . .

There, this post turned out quite long and I don’t blame you if you just skimmed it. But if you read the whole thing, THANK YOU!

The blog post about June’s second birthstone, the moonstone, need to unfortunately be postponed. I’m busy busy preparing for a rock and jewellery show that’s taking place in a month’s time, I hope you don’t mind. To see some behind the scenes on me hustling away you are more than welcome to stalk me on instagram 🙂

Until next time, I wish you a wonderful summer!

♥ Linda

Aquamarine – March Birthstone

It’s time to dig deep into the science of the gemstone aquamarine and its mineral family today. This post will definitely be more science-y than my last post about birthstones which was about the amethyst, which can be considered a fairly “simple” gemstone.

I’m so excited to teach you all about this pastel blue dream of a gemstone and its mineral family so let’s just dive right on in shall we!

The aqua stone

The name aquamarine came to surface in the early 18th century and is derived from the latin aqua marina which literally means ‘seawater’ and is of course a reference to its sea-blue colour. The gem has been a popular talisman to wear by seafarers for centuries since it was said to protect them during their travels by sea, as well as from drowning and seasickness. I might test this theory for my next time on the sea since I get seasick very easily..


Jewellery featuring the gemstone aquamarine, the March birthstone, made by Linda Sääv Jewellery.
Delicate, minimal and everyday jewellery featuring aquamarines. Made by yours truly.



The beryl family

The gemstone aquamarine is one of 8 varieties within the popular beryl family, all of which are characterized by their specific colour, and I’m sure you have heard about most of them. Beryl is a mineral which is most commonly found in granitic* pegmatites** where it has been found in epic sizes several meters tall!


Large Beryl Crystals in Outcrop and Beryl Crystal in Quartz
Left: giant beryl crystals found in 1928 at the Bumpus Quarry, Albany. Right: beryl crystal in quartz.


* The word ‘granitic’ is referred to its mineral composition, which in this case is composed of quartz, feldspar and mica, minerals that you would find in a common granite.

** Pegmatites are rock formations that form in the later stages of a granitic magma chamber’s crystallisation. Pegmatites are characterized by their larger crystal sizes which can be 2.5cm to several meters in size. The bigger crystal sizes within these rock formations is due to a very slow cooling process, which allows the crystals to grow BIG.


Granite vs Pegmatite Texture and How Pegmatites Form
Top left: granite. Top right: pegmatite. Notice the hammer in the lower left corner for scale. Lower left: where pegmatites form relative to the granitic magma it originated from. Lower right: pegmatite intrusion covering a massive cliff face.


Beryl is a beryllium aluminium cyclosilicate mineral with the chemical formula Be3Al2(SiO3)6. To explain, cyclosilicate or ring silicate refer to the arrangement of the Si (silica) and O (oxygen) atoms within the crystal structure. When it comes to the beryl, these atoms are arranged in such a way that it gives the beryl crystal its characteristic hexagonal shape.


The Hexagonal Cyclosilicate Shape of Beryl
Left: the atomic arrangement in a cyclosilicate mineral. Blue spheres are oxygen (O) and red spheres are silica (Si). Right: the hexagonal shape of the beryl, aquamarine variety.


Beryl varieties

Pure beryl is colourless, but it is frequently tinted by impurities; possible colours are blue, green, yellow, pink and red. All of these colours represent one or two specific beryl varieties.

  • Blue – aquamarine and maxixe
  • Green – emerald
  • Yellow – golden beryl and heliodor
  • Pink – morganite
  • Red – red beryl or bixbite
  • White / colourless – goshenite


Aquamarine is the blue or cyan variety of beryl and can be found at most localities which yield ordinary beryl. The deep blue version of aquamarine is called maxixe which is most commonly found in Madagascar. The pale blue colour of aquamarine is attributed to Fe2+ ions, whereas the deep blue colour of maxixe comes from when both Fe2+ and Fe3+ is present.

Advanced: The difference between the two Fe-ions is their oxidation state, which describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. If an ion looses an electron to another element in the compound it gets a higher positive charge, if it gains an electron it gets a lower positive charge. Conceptually, the oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic.

The largest gemstone quality aquamarine ever mined was found in Minas Gerais, Brazil, in 1910. It weighed over 110 kg and its dimensions were 48.5 cm long and 42 cm in diameter.


Aquamarine Specimens
Aquamarine specimens. Left and right ones are from my own private collection.



Emerald is, as most of you already know, the green variety of beryl. But spoilers, emerald is the birthstone of May which means it will have its very own blog post.

Golden beryl and heliodor

Golden beryl can vary in colour from pale yellow to a brilliant gold, with the colour being attributed to Fe3+ ions. The term “golden beryl” is sometimes synonymous with heliodor, but golden beryl refers to pure yellow or golden yellow shades, while heliodor refers to more greenish-yellow shades.


Heliodor and Golden Beryl Specimens
Left: heliodor and golden beryl beads in my own inventory. Note the slight difference in shade. Top right: heliodor. Lower right: golden beryl. 




Morganite is a rather rare gem. It is the pink variety of beryl and is also known as “pink beryl”, “rose beryl”, “pink emerald” and “cesian beryl”. It can vary in shades from light pink to rose. Orange/yellow varieties of morganite can also be found and colour banding is quite common. The pink colour is attributed to Mn2+ ions.

Pink beryl of fine colour and good sizes was first discovered on an island on the coast of Madagascar in 1910. In 1989, one of the largest gem morganite specimens ever uncovered was found in Maine, US. The crystal was 23 cm (9 in) long and about 30 cm (12 in) across, and weighed just over 23 kg (50 pounds).


Morganite Specimen and Morganite Pear Briolletes
Left: morganite with intergrown tourmaline. Right: morganite beads from my own inventory.


Red beryl

Red beryl, or bixbite, is the very rare red variety of beryl. As with morganite, red beryl gets its colouration from Mn, but from Mn3+ ions and not Mn2+ ions as in the case of morganite. As of to date, red beryl has only been found within the United States. The greatest concentration of gem-grade red beryl comes from the Ruby-Violet Claim in the Wah Wah Mountains in mid-western Utah. Unlike most other beryl varities, red beryl is usually highly included.

While gem beryls are ordinarily found in pegmatites, red beryl occurs in topaz-bearing rhyolites. Rhyolite is a volcanic rock and can be considered as the extrusive equivalent to the plutonic granite rock. Red beryl is formed by crystallising under low pressure and high temperature along fractures or within near-surface cavities of the rhyolite.


Red Beryl - Bixbite - Specimens
Red beryl. Note the high amount of inclusions. Perfectly imperfect in my opinion!



Goshenite is the colourless beryl variety and its name originates from Goshen, Massachusetts, where it was first discovered. The gem value of goshenite is relatively low and it can be found to some extent in almost all beryl localities.

Since pure beryl is colourless, one would assume that goshenite is the purest of them all. However, this assumption may not always be true as there are several elements that can act as colour inhibitors in beryl.


Goshenite Specimens
Goshenite specimens. The one on the right features an intergrown tourmaline crystal and colour impurities.


That’s a wrap

I hope you found this post interesting, I at least had a lot of fun writing it and doing some research on this interesting and beautiful mineral family.

So, if you ever want to find your own aquamarines or any of the other beryl varieties, the first step is to find yourself some pegmatite outcrops.

Happy hunting!




The February Birthstone – Amethyst

Welcome to blog post number two about birthstones (again, published in the last second). As you know I like to get science-y with these posts and probably use terms and jargons that you’ve never heard of. But I will try and explain everything as simple as possible for you. After all, I want you to understand what I’m talking about, so you can see why gemstones are so much more than just pretty minerals adorning the jewellery we wear.


Amethyst Birthstone Jewellery by Linda Sääv Jewellery


How to not get drunk

February means it is all about the amethyst! Amethyst is, as many of you may know, the purple variety within the large quartz family with a simple chemical composition, namely SiO2. Since it’s a quartz variety, it has a hardness of 7 which means it’s very suitable for jewellery since it doesn’t scratch easily from everyday wear.

Amethyst got its name from the ancient Greeks who thought amethyst would keep them from getting drunk. The word amethystos literally means “not intoxicate”. They would wear or drink out of amethyst vessels in the belief that it would prevent intoxication.


Amethyst Wine Goblet and Amethyst Dangle Earrings
Left: carved amethyst wine goblet. Right: my amethyst earrings in sterling silver.


Ultra Violet

If you didn’t know, the Pantone colour of the year for 2018 is Ultra Violet, which suits the deep purple colour of the amethyst pretty well if I do say so myself. Amethysts come however in many different purple hues, from a light pinkish violet all the way to that royal deep purple. The most valued colour of amethyst is the deep purple one and a deep purple that has a red tinge to it.

So how does amethyst get its purple colour? Simply put it all has to do with the presence of iron in its structure. Iron atoms may replace silicon atoms during the crystal’s formation. And we are talking trace amounts here, the amethyst wouldn’t be an amethyst anymore if a major part of the silicon atoms were to be replaced.

One thing that you should be aware of when it comes to the colour of the amethyst is that if it gets overexposed to sunlight, it can fade in colour. So, if you want to keep that deep purple colour of your amethyst jewellery or mineral specimen pristine, display or store it in a place with little to no sunlight.

The ametrine


Rough Ametrine Gemstone Specimen
A rough ametrine specimen with a clearly visible border between the amethyst and the citrine halfs.


Have you ever heard of the gemstone ametrine? The ametrine is a gemstone that is half amethyst and half citrine, which means it displays both purple and yellowish hues. This dual colouring is due to differing oxidation states of the iron within the crystal. And the differing oxidation states occur during the crystal’s formation (its crystallisation phase), as the temperature gradient across the crystal cools over time.

The formation of an amethyst

Amethyst crystals are always grown onto a base within a cavity of a host rock. This sort of rock with a sparkling surprise inside is called a geode.


Amethyst Geode from Brazil
Amethyst geode from Brazil. The crystals are grown onto a base consisting of agate.


Geodes are round to elongated rock structures which are hollow inside with minerals lining the walls. The base of the mineral lining is usually thin bands of translucent grey and white agate which the crystals then grow on top on. Geodes range in size from under one centimetre to several meters in length. From the outside most geodes look like common rocks, but when they are opened the sight can be breath taking. The outer wall of a geode is more resistant to weathering than the surrounding bedrock which allows it to survive intact when the surrounding bedrock weathers away.

Apart from amethyst crystals, other common geode minerals include quartz, agate and calcite. Some rare geodes can be filled with beautiful blue gem silica, pink rhodocrosite, spectacular opal or other rare materials.


Rare Geodes With Beautiful Landscapes Within from India
Two beautiful geodes with spectacular mineral landscapes within. To the left: a basalt geode with mesolite and chalcedony. To the right: a basalt geode with blue chalcedony, calcite and mordenite bobbles. Both from India.


The formation of a geode

I bet you wonder how on Earth there can exist hollow cavities within solid bedrock, so I will tell you. Most geodes are found in volcanic rock deposits such as basalts. These are rocks that normally contain a lot of gases and it’s the gases that creates these cavities. When the lava cools and solidifies, any gases that hasn’t been able to escape gets trapped and thus create cavities within. Another way a cavity can form in volcanic rocks is by liquid lava flowing out of a partially solidified lava flow. These ‘lava tube’ cavities produce some of the largest and longest geodes.


Amethyst Geodes In Basalt
Several amethyst geodes within an ancient basaltic lava flow.


Geodes can also be found in sedimentary rocks such as limestones, dolomites and calcareous shale. Within these rocks, shells, tree branches, roots and other organic materials often decay away to leave a void. These geodes are generally smaller than the geodes formed in volcanic rocks.

What all of these cavities has in common is that their mineral lining is due from mineral rich hydrothermal water or groundwater finding their way in and precipitating mineral material over a long period of time. And it’s the mineralogy of the surrounding rocks and the minerals within the water that decides which minerals will form within the geode.

So, if you want to find some amethyst crystals yourself, look for geodes within old basaltic lava flows!

. . . . .

So that’s that – I hope you enjoyed this blog post and that I managed to make you look at an amethyst in a completely new way!





The January birthstone – garnet

So, it’s been a few weeks since my last blog post. I wanted to publish this particular one a little earlier but life got in the way and I definitely under estimated how difficult it would be for me to try to explain all of these science terms in an easy and understandable way, haha! But hey, it’s still January so as I see it, I made it just in time!

January birthstone jewellery in garnet and 14k gold fill
Garnet and 14k gold fill jewellery from my birthstone collection.

Anyways, this is the first post of what will be a monthly series about birthstones. Each month I will write a post dedicated to its respective birthstone(s) and give you facts about its different properties (colour, shape, hardness), where it can be found and other interesting facts.

I’m going to let my inner geology nerd shine through in these posts which means they will be jam packed with science! But don’t worry I will try and make it fun, interesting and easy for you. My goal is to make you look at each gemstone in a completely new light.

The glorious garnet

January is of course dedicated to garnets, one of my favourite gemstones due to its beautiful colour diversity, well-developed crystal shapes and it’s geological importance (I’ll come back to that). And also, it’s my birthstone!


One of a kind green garnet earrings
One of a kind grossular garnet earrings.


Garnets have been used as a gemstone since the Bronze Age due to its commonness, beauty and durability. The word garnet can be thought of as a combination of two old words: the 14th-century English word gernet, which means ‘dark red’, and the Latin word granatus, from granum (‘grain, seed’). The second one is possibly a reference to pomum granatum (pomegranate) whose fruits contain abundant and vivid red seed covers, similar in colour to red garnet crystals.

Garnets me and my husband collected from the gold mine where we first met. These were lying in the granites surrounding the gold ore.

Garnets are common and widespread minerals and can be found all over the world. They are particularly abundant in metamorphic rocks. Metamorphic rocks are rocks that have been altered by high pressure and temperature during for example a collision that forms mountains and turns granites into gneisses or limestones into marbles.

Although garnets form in all of the colours of the rainbow, garnets are often easy to recognize because they are generally found as well-developed crystals in a cubic crystal form, usually occurring as dodecahedrons, trapezohedrons or a combination of the two. I know, I know, you have no clue what those words mean, but the picture below might do the trick.

dodecahedron and trapezohedron combos
The many looks of garnets. Top row: dodecahedron (far left) and dodecahedron + trapezohedron combinations. Bottow row: trapezohedron (far right) and trapezohedron + dodecahedron combinations.

The geological importance of garnets

Garnets are more than just beautiful, they play an important role for geologists trying to figure out the genesis of garnet-bearing rocks. Garnets work like record keepers, they store the conditions of which they were formed and altered in. This means that geologists can figure out the temperature and pressure and hence the depth of where a garnet-bearing rock originated. This particular science is called geothermobarometry and was one of my favourite subjects when studying geology! I felt like a detective, figuring out where a particular rock came from and what it had been through since its formation.

The many species of garnets

So, garnets come in a wide variety, can you guess how many garnet species there are? Fifteen! They all follow one general chemical formula: X3Y2Si3O12 , where X can be either calcium, ferrous iron, magnesium or manganese, and Y can be either aluminium, ferric iron, chromium, manganese, silicon, titanium, zirconium or vanadium.

The six largest and most common species are:

  • Almandine Fe3Al2Si3O12
  • Pyrope Mg3Al2Si3O12
  • Spessartine Mn3Al2Si3O12
  • Grossular Ca3Al2Si3O12
  • Andradite Ca3Fe2Si3O12
  • Uvavorite Ca3Cr2Si3O12

Now, this is where it gets complicated, so bear with me as I try to explain. These six garnets are known as end-members and can be divided into two groups. Each group consists of three garnets which simply put mixes with each other during crystallization in what is called solid solution series. This means that almandine (Fe) can mix with both pyrope (Mg) and spessartine (Mn) and grossular (Ca) can mix with both andradite (Fe) and uvavorite (Cr).

With mixing I mean that a garnet is never 100% purely an almandine (100% Fe) for example. There is always a little bit of pyrope (Mg) or spessartine (Mn) mixed in. The name an individual garnet specimen is given is based on the chemical composition and the element (Fe, Mg or Mn) that has the highest percentage.

So, for example, if a garnet is analysed having 80% Fe, 10% Mg and 10% Mn in its composition, that garnet would be classified as an almandine. If a garnet has 60% Mg, 30% Fe and 10% Mn in its composition, it would be classified as a pyrope. And so on. If you take a look at the triangle below though, you see that the mixing has its limits. The yellow area represents the area of all the observed compositions found in garnets. The limitations are due to elemental behaviour during crystallization. I will not go into this further because this is a whole other very complicated topic.


The pyralspite garnets solid solution series. Each point of the triangle is dedicated to one of the three end-members and the yellow area represents their mixing area.

How to distinguish between the 6 most common garnets species

Although you can’t be 100% sure of what type of garnet you are looking at without a chemical analysis done in a lab, there are some features you can use to at least narrow down your guesses. Its colour and where you found it can give you some clues. So if you have some garnets laying around at home that you’d like to try and classify, read on! Below follows some short descriptions for each (major) garnet species that might be able to help you out during your detective work.


My private collection of garnet crystals. From the left: hessonite, spessartine, spessartine, grossular, demantoid, chrome grossular and tsavorite.


Almandine is the most common garnet species and have that deep red colour which garnets most often are associated with. Almandine garnets can be found in granites as well as in metamorphic rocks like mica schists and gneisses.

Pyrope is a fun garnet species because this garnet is an indicator mineral for high-pressure rocks such as diamond-bearing kimberlites, which means that they are used in diamond prospecting! Pyrope normally varies in colour from deep red to black which can make it hard to distinguish from almandine. Rhodolite is a violet-red to pink hued variety of pyrope which chemically is a 2:1 mixture of pyrope and almandine. Colour change or blue garnet is another variety of pyrope which is a mix of pyrope and spessartine. This is the rarest type of garnet. Apart from being found in kimberlites it can also be found in volcanic rocks, which means rocks that have been ejected on to the surface during a volcanic eruption.

Spessartine is most commonly known for its beautiful orange-yellow colour which it gets from the manganese in its composition. Spessartines are mostly more or less orange but they can also be coloured red by substituting the manganese with iron. A vivid bright tangerine orange variety has the aptly name mandarin garnet. Gemstone quality spessartine is rare but is most often found in granite pegmatites.

Grossular garnet can be colourless all the way to black, but it got its name from the green variety which resembled the gooseberry (grossularia) in colour. Other grossular varieties like hessonite are cinnamon brown to orange-red in colour. Tsavorite is a variety which is vividly green in colour. Chrome grossular is a bright green variety, often mistaken for uvavorite. Grossular is commonly found in contact metamorphosed limestones.

Andradite may be red, yellow, brown, green or black. There are three recognized varieties of andradite garnets: topazolite, demantoid and melanite. Topazolite is golden-yellow to olive coloured. Demantoid is yellow-green to emerald-green and has been called the ‘emerald of the Urals’, it is one of the most prized garnet varieties. Melanite crystals are opaque and black. Andradite garnets are commonly found in contact-metamorphosed limestone and in mafic igneous rocks.

Uvavorite is a rather rare garnet species which is bright green in colour. Uvavorite crystals are brittle and almost always too small to be cut as gemstones. Some of the largest crystals come from Outokumpu, Finland. Uvavorite is found in chromium-bearing rocks such as serpentines.

That’s all folks

I hope you enjoyed my first more science-y blog post about garnets. I had a lot of fun writing it but I have to admit, it took me quite a while and I’m still not sure I managed to explain everything good enough. But I had a deadline to stick to and hopefully I will get better at explaining with each birthstone post I write!

If you liked this post or if you have any questions about anything, please leave a comment 🙂