The ABC’s of Gemstones


Here is the alphabet or ABC's of gemstones just because there's just so many and much to know.  So I'm going to break it down for you one letter at a time.  I'm taking this alphabet one day at a time so check back daily to get your ABC's in Gemstones!


A is for Amber, Agate & Ammolite

Amber is tree resin that has fossilized over time and sometimes contains inclusions of plant or animal material, if you’re lucky.  Amber occurs in a variety of colors as well as the usual orangy-yellow-brown colour that is associated with the color amber.  Amber can range from white to pale bright yellow to brown and deep brownish black.  Ancient Germans called amber 'bernstein', or 'burn stone' because they burned amber as incense.  Clear colourless amber was considered the best material for rosary beads as it is smooth and silky to the touch.  Common amber is cloudy and opaque, whereas more highly priced amber is transparent.

Agate is a chalcedony quartz that forms in a wide variety of colours and textures, often in concentric layers.  Agate is characterised by it’s microcrystalline structure and brightness of colour.  The different agate forms include carnelian agate (reddish hues), blue lace agate, plume agates, moss agate, Botswana agate, fire agate, crazy lace agate/Mexican agate and eye agate among other varieties.

Ammolite is a valuable opal-like organic gemstone, made of the fossilized shells of ammonites which were cephalopods, or squid-like creatures.  Ammonites lived in tropical seas until the end of the Mesozoic era which was also the end of the dinosaurs. The fossilized shells that make up ammolite are composed mainly of aragonite, the same mineral that makes up nacreous pearls.  Ammolite is found along the eastern Rocky Mountains of North America and is the official gemstone of Alberta since 2004.   The quality of gem ammolite is determined by the number of primary colours, the way the colours play and the brightness of colours (iridescence).  All spectral colours found in nature are contained in ammolite and each colour represents a different layer of the gem.   Every ammolite gem shows a unique display of colour.  Never easily nor often imitated, ammolite only resembles a few gemstones: labradorite and broad flash black opal. 

B is for Beryl

Beryl is a species of gemstones which contains several varieties based on colour.  Pure beryl is colorless, but it is frequently tinted by impurities; which creates the potential colors such as green, blue, yellow, red, and white.   Blue aquamarine, green emerald, pink or peach morganite, yellow helidor, white goshenite and the most rare red bixbite. All from the same species although the price of the varieties varies depending on mining locations and rarity.


C is for Citrine, Corundum and Chalcedony

Citrine is the birthstone of November and member of the huge quartz family. This is a great gemstone with a durable hardness of 7 on the Mohs scale and relatively resistant to scratches. In the world of gemstones there are few yellow gems; although diamond and sapphire are yellow their expense may inhibit a buyer. Citrine occurs in shades from lemon yellow to deep reddish brown. Amethyst and smoky quartzes can be heated to become yellow, this today is very common in the trade but can only be recognised by a trained specialist.

Chalcedony is a  cryptocrystalline form of silica, which has a waxy luster waxy luster, and may be semitransparent or translucent.  Chalcedony assumes a wide variety of colors, but the most common are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black.  Each colour is it's own variety. 

Agate is variety of chalcedony with multi-colored angular or curved banding. 
Aventurine is is a form of chalcedony, translucent and containing platy mineral inclusions that give a shimmering effect termed aventurescence.  
Carnelian is a clear-to-translucent reddish-brown variety of chalcedony; the hue may vary from a pale orange, to a deep nearly-black coloration.  
Chrysoprase is a intense green variety of chalcedony, colored by nickel oxide.
Heliotropealso known as bloodstone, is a green form of chalcedony containing red iron oxide inclusions which resemble drops of blood.
Moss agate contains inclusions that resemble filaments providing the superficial appearance of moss or blue cheese. 
Onyx has black and white banding 
Sardonyx is a variant of onyx with brown, red, orange and white banding


Corundum is naturally clear, however it comes in in every colour due to colour inducing impurities; red is ruby and everything else is sapphire. The line between red ruby and pink sapphire is the saturation and tone of the hue and the amount of chromium contained in the stone that gives that gorgeous red colour. Ruby comes in the star variety and sapphire comes in black and blue star sapphire. Pink-orange sapphire is a unique and labeled padparadscha sapphire.


D is for Diamond

Often imitated never duplicated, diamond is the most desired of all gemstones with round brilliant cuts being most popular.  Diamonds are mined in Central and Southern Africa, Australia, Russia and Canada.  Commercial deposits are actively mined in the Northwest Territories of Canada.  Diamond price is dictated by the carat weight, clarity, colour, cut and finally the certificate of a diamond. Although diamonds are desirable for their lack of colour, fancy coloured diamonds are a unique choice coming in nearly every colour.  Small defects in the chemical composition, or impurities of about one per million of lattice atoms create colours such as blue (boron), yellow (nitrogen), brown, green (radiation exposure), purple, pink, orange or red.  Worldwide cutting centers are located in Belgium, United States, Israel and India.


E is for Emerald

We covered emerald with beryl but as the most expensive stone of the family, let's go more in depth.  Emerald contain a host of mineral inclusions and is a naturally fractured stone filled with fissures.  With emerald you should expect eye visible inclusions, to tell you it's natural, otherwise it might not be real.  Eye clean emeralds are extremely expensive and even more rare in large sizes.  When emeralds are extracted from the mine, they are traditionally soaked in resinous cedar oil to fill the fissures, fractures and improve the stone's clarity and colour.  This is commonly accepted practice with emeralds and much care must be taken by jewellers when setting these stones, not to apply heat, which will damage the emerald.  Over time the cedar oil does come out but stones can be re-oiled to restore their natural beauty.  


F is for Fluorite

Fluorite is dubbed "the most colorful mineral in the world"; the most common colors being purple, blue, green, yellow, or colourless. Much less common are pink, red, white, brown, black, and almost every shade in between. The colour of fluorite is decided by factors such as impurities, exposure to radiation, and size of the colour centers.  With only a hardness of four on the Mohs scale, fluorite is a fragile stone, less common than other coloured stones found in jewellery.  Fluorite often has multiple colours of colour zoning or banding; this zoning corresponds to the shape of fluorite`s crystals which makes a specimen more desirable to collectors.


G is for Garnet

Since the bronze age, garnet has been used as gemstones and abrasives.  Within the garnet group, there are different species that contain a variety of colours due to their different chemical compositions.  Pyrope and almandine are the most well known garnets are the red and purplish reds which when in a mix of both, are called rhodolites.  Grossular garnet is a species which includes orange hessonite and green tsavorite garnets.  Demantoid garnet is from the andradite garnet group which contains a unique horse tail inclusion, which is rare and expensive.  Demantoid garnets also occur without the horsetail, but are less desirable to collectors.  Spessartite is an orange-yellow variety of garnet mined in Madagascar.


H is for Hematite & Heat Treatment

Hematite is also spelled as haematite, is a mineral which is mined as the main ore of iron. Hematite is coloured black to steel, silver-grey, brown, reddish brown or red. Hematite is harder than pure iron and more brittle. Brown iron produces the golden yellow colour of tiger’s eye quartz and often occurs in tiger’s eye layered banding.

Gemstone colour and clarity can be improved with heat treatment.  Heat treatment is a common practice for many stone types including, ruby, sapphire, aquamarine, topaz and tanzanite. Heat treatment is the continuation of the process that occurs in the earth when the stone was originally formed.  Understand that treatments enhance a gem to let it's beauty shine, similar to the process of dying your hair or polishing your nails.  Aquamarine is heated to remove yellow tone and alter the green element to a more blue colour which is how most people imagine aquamarine to look.  Tanzanite would not exist unless heated to remove brown undertones and enhance the violet blue colour tanzanite is known for.  The world demand for gem quality corundum, ensures that ruby and sapphire are routinely heated to improve the clarity and colour.  Heat treatment is permanent in gemstones and is common practice.  Due to the large amount of heated gems in the world market, unheated ruby and sapphires with excellent clarity and colour can command a premium price.  Citrine is often amethyst heated to until the colour changes.  Ametrine is citrine partially heated to product gradient results; partly amethyst and part citrine.  All treatments should be disclosed to customers, however sometime they are not due to the commonality of the heating, so asking about treatments when buying a gemstone is certainly encouraged.  Knowing your gem is treated can prevent disastrous results with your jeweller.  Emeralds should not be heated, especially if they are treated with cedar oil, as the heat will remove the oil and could even cause the stone to fracture.  Diamonds must be protected with boracic acid when heating to prevent the surface from being burned on the surface or even completely burned up. So the lesson here is ask about treatment, if only to protect your potential investment.


I is for Iolite

Iolite is the transparent variety of Cordierite, used commonly as a gemstone.  Iolite that is gem quality is sometimes used as a reasonably priced substitute for Sapphire and Tanzanite.  Iolite has extreme pleochroism and is often a trichoic stone that shows three hues when viewed at different angles, violet, blue and colourless. Iolite colours vary from a bright sapphire blue to blue violet to yellowish gray to light blue as the light direction changes. Iolite is a much softer stone than sapphire, so it cannot stand the damage of daily use as ring but it's great for pendants and earrings. Iolite was likely the world's first polarising filter; Viking mariners used thin pieces of Iolite to navigate during their travels.



J is for Jade

Jade artifacts from prehistoric excavations are simple beads, buttons and tube shapes.  There are two very different types of jade; Nephrite and Jadeite, both jades are ornamental.  Jadeite jade is rarer and prized for its bright emerald-green colour but also occurs in pink, lavender, orange, red, black and some brown colours. The translucence can vary from solid to opaque to nearly clear.  Nephrite jade occurs mostly in greens and grey with the occasional yellow white or brown.  The current main source of nephrite is in Canada.


K is for Kunzite

Kunzite is a relatively young gemstone named by jeweller and specialist George Frederick Kunz in 1902.  Kunzite is a delicate pink hue, with clarity and often displays a hint of violet, but the colour is dependent on the cutting to display a violet, pink or colourless gem.  Due to this phenomenon, kunzite is known as a pleochroic gemstone. This gemstone is part of the spodumen family which includes diopside, jadeite, hiddenite and three other spodumens.  Kunzite can face in direct sun, so jewellery containing this gem should never be worn at the beach.  As with other gems, the more colour, the higher the price due to its rarity. 


L is for Labradorite & Lapis Lazuli

Labradorite is an amazing gemstone that exhibits a play of colours called labradorescence, which is the result of light refracting within the stone.  This gemstone is the namesake of its origin, on the Labrador Peninsula in Canada, although it is found in other countries.

Lapis Lazuli is made up of a combination of minerals including calcite, sodalite, pyrite and mainly consists of diopside and lazurite.  Afghanistan produces the best specimens in the world, that can be made into jewellery, carvings, boxes, mosaics, vases and ornaments.  Lapis has been a popular stone for thousands of years and traditionally was ground and processed to make the ultramarine pigment for tempera paint.  Lapis prices like other gemstones is dependant of the intensity and the beauty of the colour. 


M is for Moh’s Scale of Hardness

Moh's scale of hardness is a test devised by mineralogist Freidrich Mohs as a way of measuring the relative hardness of a gemstone.  The Moh's scale ranges from one to ten, being the hardest on the scale.  The principal of the test is that a lower numbered stones cannot scratch a higher numbered stone.  This test can be used to aid identification but us no longer used as it is destructive. Even though this test refers to the stones hardness, it has nothing to do with the toughness of a stone and is actually about how easily a stone scratches another. 

This Moh's Scale of Hardness

1.Talc.  2. Gypsum.  3. Calcite.  4. Fluorite.  5. Apatite.  6. Orthoclase.  7. Quartz.  8. Topaz.  9. Corundum.  10. Diamond.


N is for Natural Gemstones

What is a natural gemstone anyway? Natural gemstones are formed in nature with no intervention from humans.  Natural gemstones include organics such as amber, coral, pearls and shell as they are rocks with an orderly crystalline structure and fixed chemical composition.  The other criteria for a gemstone is beauty, rarity and durability.  


O is for Opals

Opals come in various body colours, from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black; Opal variations are virtually unlimited.  Opals display a phenomenon refereed to as play of colour which occurs due to the silica gel inclusions that reflect and diffract light within the opal.  The price of opal depends on the type, amount of iridescence displayed and colours.  White and greens are most common and reds against black are the most rare and thus costly.  Nearly 95% of all fine opals come from the outback in Australia although this is changing with Ethiopian specimens coming into the market.   Opals have a high moisture content, are very porous and require special care. Often the thin layer of opal is attached to a backing and may even be re-enforced with another material on top; known as opal triplets or doublets.  This is very common and is often the only way certain opals can be set as they are so delicate.  More expensive opals do not need a base or coating to be protected. 


P is for Pearls

Pearls are created when an oyster covers a foreign object in concentric layers of nacre made of calcium carbonate in crystalline form.  Ideally a pearl is perfectly smooth and round, but there are many variations and shapes that occur resulting in baroque pearls among others.  Pearls are an organic gemstone and were once only created in nature, “wild” and without any human intervention.  Pearls today cultured by humans and natural pearls are even more rare and wild.  Gem quality pearls are nacreous and iridescent.  Pearl quality is decided by the orient, which is the soft iridescence refracted between the layers of nacre.  The finest pearls have a smooth even surface, with no flaws or spots on the nacre.  Freshwater pearls are abundant and come in endless colours thanks to permanent treatments.  Pearl value is affected by the size, colour and regularity if the shape.


Q is for Quartz

Quartz comes in so many different varieties including amethyst, citrine, ametrine, rose quartz, smoky quartz, tiger’s eye, onyx, agates, chrysoprase, rutilated quartz, tourmalinated quartz, carnelian, rock crystal, druzy quartz, chalcedonies, and other varieties.  Quartz is an abundant mineral and thus offers an affordable price not to be taken for granted in jewellery and carvings. 


R is for Ruby

We covered ruby with corundum but as one of the most valuable gemstones let’s go a little deeper.   Ruby colours vary from pink to blood red due to the presence of chromium.  Only red corundum can be called ruby, everything else is sapphire.  Rubies of more than 3 carats are very rare due to the chrome which colours this gem, which causes fissures and cracks within ruby crystals.  Rubies sometimes exhibit a silky shine or ‘silk’, which is caused by fine rutile needles; which in abundance creates asterism which we know as star ruby. 


S is for Sapphire

Sapphire is mainly thought of as blue but occurs in ‘fancy’ colours of yellow, pink, orange, purple white and green. Sapphire is a member of the corundum group and has an excellent hardness of 9 on the Mohs scale which makes is a great choice for everyday wear. Kashmir sapphires are the finest and most valuable followed by Burmese sapphires and then Ceylon or today’s Sri Lanka.


T is for Tourmaline

Tourmaline is referred to as the ‘gemstone of the rainbow’ because it occurs in an incomparable variety of colours.  Tourmaline is a dichroic gemstone, so depending on the angle from which you look the colour may be different or vary in intensity; although always more intense when viewed toward the main axis.  Tourmaline often comes with two colours, known as bicoloured tourmaline.  If the centre of a tourmaline is red and the area around it green it is given the nickname ‘watermelon’.   There are colour change tourmalines, cat’s eye tourmaline and even neon coloured Paraiba tourmaline.  Paraiba is often heavily included and often comes in intense blue and green, thanks to the element of copper which colours the stones.

U is for Unakite


Unakite is a variety of jasper which is also known as epidote. Unakite appears in shades of pink and green with a mottled appearance; n altered granite comprised of pink orthoclase feldspar, green epidote and colourless quartz.   Unakite in good quality is often used in jewellery, carvings such as animals, decorative eggs and spheres. 


V is for Variscite

Variscite is often confused with turquoise, however variscite is mostly greener in colour.  Variscite with a Nevada origin usually contains black spiderwebbing in the matrix, which makes it easy to confuse with green turquoise. Sometimes the variscite contains veins of the mineral crandallite.   Variscite is popular for ornamental use, carvings and jewellery. 


W is for Wavellite

Wavellite was named after W. Wavell, the discoverer of this mineral.  Wavallite occurs in various colours from white to yellow, green or black and usually in a hemispherical radial structure which may mimic cats-eye.   


X is for X-Ray

X-Ray examination is used in gemmology for the identification of natural pearls.  A natural pearl shows a series of concentric growth rings, whereas the cultured pearls are different altogether.  With cultured pearls a shell bead is implanted as a nucleus, and the oyster then secretes layers of nacre over the outer surface of the implant before it is removed after a minimum of six months.  A cultured freshwater pearl will reveal the solid centre of the shell bead when X-rayed.  A beadless cultured pearl often shows growth rings but also a central cavity where the pearl sac once was. 


Y is for YOUNGITE

Youngite is a type of agate or jasper coated by druzy quartz crystals.  This is a composite gemstone and the druzy quartz looks fuzzy and grey in colour with a jasper centre which can be anywhere from light tan colour to a peach or salmon colour.  Youngite usually fluoresces under a black light.


Z is for Zircon and Zoisite

Zircon is a mineral which is often a substitute for diamond when colourless.  Zircon comes in yellow-golden, red, pink, brown, black, blue and green colours.  Large crystals of zircon are rare.  The colour of zircon can be changed with heat treatment; depending on the colour to a blue, colourless or golden-yellow colour. 


Zoisite
may be blue to violet, green, brown, pink, yellow, gray, or colorless.   Blue zoisite is called Tanzanite, and occurs in only one place in the world, Tanzania.   Due to its low hardness, tanzanite should always be worn carefully, it is a brittle stone.  Tanzanite was discovered in 1967 and named by Tiffany’s after the place where the stone had been found.   Nearly 90 of all tanzanite merchants are official members if the International Colored Gemstone Association (ICA) and bound by the ethical high standards of this organization. Tanzanite is polychromatic, so depending on the angle you view from the stone can appear blue, purple, or brownish-yellow.   Most raw tanzanite occurs in brownish-yellow colours, which is then heated to achieve the desired blue-violet colour. 

 


Check back tomorrow to get your ABC's in gemstones!


1 comment


  • Priscila

    I’s pretty silpme- I’d like to win these earrings so I can have something to be excited about. Being a single, working mom, it’s easy to say, the hell with gettin’ dressed! and lose yourself in a world of excuses that get you arrested by the fashion police! In the new year, I don’t want to be that Mommy! Every once in a while, it’s nice to feel sexy and fashionable with a silpme accessory like a funky bracelet, an exotic necklace, or some sizzling hot earrings that tell people you’re not so ordinary after all. Even better, it’s nice to throw people for a loop. ; )


Leave a comment


Please note, comments must be approved before they are published