GEMSTONE GUIDE: SEMI PRECIOUS STONES
What are semi-precious stones?
A semi-precious stone is also known as a gem or gemstone (also a jewel, a gem, a precious stone) is a portion of mineral, which, in refined and cut form, is used to create jewelry or other embellishments. There are also organic resources or precise rocks that are not minerals (for example jet or amber) that are also used for jewelry and would also be considered to be gemstones as well.
In the West, precious stones are diamonds, sapphires, rubies and emeralds. All other stones are considered semi-precious stones. However, this is a commercial based classification and was a distinction that marketers created years ago which gives the false impression that precious stones are more valuable than semi-precious stones.
What’s the difference between a semi-precious stone and a precious stone?
Precious stones and semi-precious stones are terms that were created in the mid-1800’s to describe gemstones, which were categorized solely based on their rarity. Stones found in abundance were labeled semi-precious, and a stone that was rare would be categorized as precious and more valuable.
Diamonds, rubies, sapphires, emeralds were classified as precious stones. All other stones are classified as semi-precious stones.
The distinction between precious and semi-precious stones is their rarity and their quality. Despite this distinction and classification of precious stones vs. semi-precious stones, it is not necessarily true that a precious stones is always more valuable or rare than a semi-precious stone.
For example a green garnet known as Tsavorite is classified as a semi-precious stone, however, it is more valuable than an emerald, which is classified as a precious stone.
Now, value is measured by several different factors, and precious stones often do not hold more value than semi-precious stones. However, the label is still valuable and is used worldwide to promote and sell jewellery.
SOME OF THE MOST POPULAR SEMI-PRECIOUS STONES
Agate – No gemstone is more creatively striped by Nature than agate, chalcedony quartz that forms in concentric layers in a wide variety of colours and textures. Each individual agate forms by filling a cavity in host rock. As a result, agate is often found as a round nodule, with concentric bands like the rings of a tree trunk. The bands sometimes look like eyes, fanciful scallops, or even a landscape with trees.
Alexandrite – Alexandrite is the the color-change gem, in daylight, it is a cool bluish mossy green. Inside in lamplight, it is a red gem with a warm raspberry tone. You can see this by switching from fluorescent to incandescent light. The value of the gemstone increases as the color change becomes more distinct. It’s said to strengthen intuition, aid in creativity and inspire the imagination. Originally discovered in Russia’s Ural Mountains in the 1830s, it’s now found in Sri Lanka, East Africa, and Brazil. It is both rare and valuable. Alexandrite is the birthstone of June.
Amber – Amber is fossilised Pine tree resin. Demand is especially strong for amber with insects inside it. There are five classes of amber, defined on the basis of their chemical constituents. Because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions.
There are many myths surrounding the origin of amber. Ovid wrote that when Phaethon, a son of Helios, the sun, convinced his father to allow him to drive the chariot of the sun through the heavens for a day, he erred too close to the earth, scorching it. To save the earth, Zeus struck Phaethon with a thunderbolt and he died, plunging out of the sky. His mother and sister turned into trees in their grief but still mourned him. Their tears, dried by the sun, are amber.
Amethyst – For centuries, Amethyst has been associated with many myths and legends as well as religions in numerous cultures. Not only is it the beautiful color that makes this gem so popular but it is also widely available in difference shapes and sizes which makes it more affordable. Amethyst complements both warm and cool colours so it looks fabulous set in both yellow and white metals. This unique ability means it enhances almost every color in your wardrobe. Amethyst is the birthstone of February.
Aquamarine – The name Aquamarine speaks for itself, meaning seawater. For centuries, this timeless gemstone has been a symbol of youth, hope, health and fidelity. Since this gemstone is the colour of water and the sky, it is said to embody eternal life. It was long thought that Aquamarine has a soothing influence on married couples, making it a good anniversary gift. Aquamarines are found in a range of blues; from a pale pastel to a greenish-blue to a deep colour. Darker shades of blue are increasingly rare and in turn, make the value increase. Aquamarine is frequently a pastel gemstone but the color can be more intense in larger gemstones. Aquamarine is the birthsonte of March.
Aventurine – Aventurine is a form of chalcedony (quartz) that contains small inclusions of various shiny minerals. These materials, usually spangles of mica or iron oxide, give the stone a glistening effect known as aventurescence. Aventurine’s granular appearance and particular translucence are its most distinctive characteristics. Most aventurine is naturally reddish brown or yellow, though a green variety is also known. The green aventurine you’ll find on the market, as well as the red and blue, is almost certainly dyed to achieve its color. The mineral aventurine is named for its resemblance to the well-known aventurine glass of Venice, Italy.
Beryl – Beryl is a mineral composed of beryllium aluminum cyclosilicate. It is a very popular mineral in all of its forms. The hexagonal crystals and can be found in small to very large sizes. Pure beryl has no colour and is known as “goshenite,” but transparent crystals with inclusions and impurities are different colours and are known as gemstones with different names. Colours range green to blue to red, yellow, and white. Green beryl is caused by traces of chromium. The deep green variety of beryl is emerald, one of the most precious gemstones. The light green shade of beryl is known simply as “green beryl.” Green beryl is sometimes heat treated to create aquamarine. Yellow or golden beryl is known as “heliodor,” and blue beryl, caused by traces of iron, is known as aquamarine. Pink beryl is “morganite,” and the deep red variety of beryl, is known as “red beryl” or “bixbite.” Bixbite is very rare and therefore expensive. It can only be found in two locations in Utah.
Chalcedony – Chalcedony is a catch-all term for cryptocrystalline quartzes (quartz with microscopically small crystals). As a marketing term in the gemstone industry, however, “chalcedony” refers more specifically to semitransparent or translucent chalcedony with a solid colour (commonly pale bluish-gray). It is brittle and has a waxy, dull luster. It may be semitransparent or translucent and is vitreous when polished. It can also be white, blue, purple, pink, yellow, orange or red (but not orange-red, as that stone is known as carnelian). Blue and purple are the most popular hues. The chalcedony family as a whole includes agate, jasper, carnelian, chrysoprase, onyx, bloodstone, aventurine, flint, chert and sard. Chalcedonies can be either transparent or translucent, solid or patterned. The most common forms are agate and jasper.
Carnelian – Carnelian is an A-grade agate. What a lot of people call ‘true carnelian’ is the fiery red/orange colour, and in theory, carnelian is naturally that colour. However, most of that fiery red/orange “true” carnelian is heat-treated in secret before it reaches the gemstone-cutting factory. This apparently has been a secret for thousands of years; each part of the world thought everyone else’s carnelian was naturally red, but they were heating theirs, too. When held against the light, the colour-treated carnelian shows its colour in stripes, while natural carnelian shows a cloudy distribution of colour. The name carnelian is said to be derived from the Latin word carnis (“flesh”) due to its colour.
Coral – Coral is a calcium carbonate built up by the skeletal material of small animals that live in colonies in the sea. It comes in a wide range of colours, with black, red and pink considered the most valuable. It appears dull and matte when unfinished, but gains a beautiful gloss after polishing. It often grows in branches that look like underwater trees, and most is found in the Mediterranean Sea and in the Pacific Ocean off Japan and Taiwan.
Many people think coral, like ivory, must be protected and/or is an endangered species. However, the few threatened coral reefs are monitored by international law. is an A-grade agate. What a lot of people call “true carnelian” is the fiery red/orange colour, and in theory, carnelian is naturally that colour. Furthermore, research shows that at current harvesting levels, even the Great Barrier Reef’s coral is sustainable; in other words, it replenishes itself at a rate equal to or greater than it is collected.
Citrine – The name Citrine, which is French for “lemon”, fits well with its color range of juicy lemon yellow to a bright orangey brown. Most people choose a Citrine based on their personal preference, but some of the most sought-after Citrine gemstones have a clear, radiant yellowish to brownish red color. In ancient times, Citrine was carried as a protection against snake venom and evil thoughts. Today, Citrine is known as the merchant’s stone and is associated with success and prosperity. Citrine is one of the most popular and affordable gemstones. It is relatively plentiful and available in a wide range of sizes and shapes, including very large sizes. Citrine is a birthsonte of November.
Flourite – This common and pretty pastel mineral typically occurs in vein deposits. The name fluorite comes from the Latin fluo ‘flow’ in reference to its use as a flux. A flux is a substance that promotes the flow and combination of other materials, and fluorite is often used in making steel and other metals that require the removal of impurities. Another interesting aspect of the gemstone is its fluorescence in ultraviolet light. In fact, the word ‘fluorescent’ is derived from fluorite.
Garnet – This gem is available in a rainbow of colors, from the deep red Bohemian Garnet to the vibrant greens of the Russian Demantoid and African Tsavorite. We also see it appearing in the oranges and browns of Spessartite and Hessonite from Namibia and Sri Lanka and the subtle pinks and purples of Rhododendron. Legend says Garnets protect their owners from nightmares. Garnets have long been carried by travelers to protect against accidents far from home. Garnet is the birthstone for January but with its stunning variety of colors and its mystical powers it has been given as a gift for all occasions for centuries. Garnet is a birthsonte of January.
Iolite – Iolite is a variety of the mineral cordierite. This mineral was named after French geologist Cordier. The name iolite comes from ios, the Greek word for violet. Iolite is commonly known as “water sapphire” in its deep blue sapphire color. Like sapphire and tanzanite, its fellow blue gemstones, iolite is pleochroic- meaning it transmits light differently when viewed from different directions.
The Viking mariners used thin pieces of it as the world’s first polarising filter. Looking through an iolite lens, they were able to determine the exact position of the sun, and navigate their way safely to the New World and back. The property that made iolite so valuable to the Vikings is its extreme pleochroism. Iolite has different colours in different directions in the crystal. A cube cut from iolite will look a more or less violet blue, almost like sapphire, from one side, clear as water from the other, and a honey yellow from on top. In the past, this property led some people to call iolite ‘water sapphire’, though the name is now obsolete.
Jade – Jade is a green stone given in celebration of the 12th, 30th, and 35th anniversaries of marriage. For thousands of years, the stone has been revered in China and other countries throughout the world. The Chinese, Mayas, Aztecs, and the Maoris of New Zealand have long prized the stone for its use in jewelry, and in carvings of sacred religious figures. Before there were written records of jade, it was used for axe heads, spear points, daggers, and sacred knives in pagan religious ceremonies. From the earliest days of jade’s history, it has been the most favored gem among the Chinese. There are collections of jade with Chinese carvings, dating back to 2000 BC in museums throughout the world. These include carvings of meaningful shapes such as fish, birds, bats and dragons. Jade was used extensively in daily and ceremonial objects of Chinese nobility and represented high rank and authority.
Jet – Jet is a product of fossilized wood. It is similar to coal, but harder and more durable. Jet actually comes from a particular tree, called Araucaria, which was a conifer tree from the Jurassic period, about 180 million years ago. When the trees died, some fell into swamps or rivers, broke up, and were carried out to sea. As the trunks and branches became wet, they sank to the bottom of the ocean. Eventually, pressure from the multiple layers of organisms and mud flattened the tree fragments together, and together with chemical changes, altered the wood to jet. In the UK Whitby beach is a famous source of Jet.
Kunzite – Kunzite is a very young gemstone, comparatively- it has only been known for a little more than a hundred years. In 1902, George Frederick Kunz, a gemstone specialist and New York jeweler, was the first person to give a comprehensive description of the stone. Kunzite had just been discovered in the Pala District of San Diego County, California. The new and beautiful gemstone was named “kunzite” after its discoverer, Mr. Kunz.
Kunzite is the pink to violet variety of the spodumene family and spodumenes make up the pyroxene group. The word ‘pyroxene’ is derived from the Greek words ‘pyr,’ meaning ‘fire’ and ‘xenos,’ meaning ‘stranger.’ Kunzite gets its beautiful range of seductive and feminine lilac-pink colors from the presence of manganese. The gemstone has a glassy transparency and is highly pleochroic; it changes colors from a pale pink to a light violet or sometimes even colorless, depending on the angle in which it is viewed.
Moonstone – This enchanting gemstone belongs to the large mineral group of the feldspars, of which almost two thirds of all the rocks on Earth consist. Moonstone is the birthstone for the month of June and the stone traditionally given in celebration of the 13th anniversary of marriage. Moonstone has always been very popular in India. The stone was also prized by the Romans, who thought it was magically formed out of moonlight. Moonstone was used in Roman jewelry since the year 100 AD. Ancient Greeks and Romans both linked the stone with the moon deities. Moonstone comes from the mineral family feldspar, which is one of the most plentiful in the world, however fine gem quality moonstone is scarce and is becoming more scarce as time goes on. Moonstone was very popular in the Art Nouveau jewelry of the early 20th century and continued to flourish until around 1925 in the US. Men wore the stones in stickpins for their ties, in cuff links, rings and mounted as ornaments on watch chains. Women wore moonstones in bracelets, brooches, rings, earrings and necklaces. Moonstone is the birthstone of June.
Morganite – Morganite is the official gem of Madagascar. Morganite is also sometimes known as vorobevite. Morganite was actually named after the famous banker and gem enthusiast, J. Pierpoint Morgan. It is a beryllium aluminum silicate, a rare pink variety of beryl, and usually ranges in pink colour from pink to rose to peach and violet. As with most gemstones, the more richly coloured the specimen, the higher it is prized.
Very rarely, bi-coloured stones are found that are part-morganite and part aquamarine, but these are museum pieces. Morganite is not common but the specimens that are found are usually medium to large. Morganite is never produced synthetically and because it is one of the most rare varieties of beryl, it tends to be very expensive. Morganite occurs as short and stubby tabular prisms and is dichroic, showing either two shades of the body colour, or one shade and colourless. Morganite is actually essentially colourless, but impurities of magnesium give the stone its pink colour, while iron impurities give the stone a yellowish or orange tinge. Heating the stone, is an acceptable practice and reduces the iron content, thereby resulting in a more beautiful pink stone.
Opal – In ancient times, the Opal was known as the Queen of Gems because it encompassed the colors of all other gems. Each Opal is as unique as a fingerprint. With its rainbow of colors, as you turn and move the Opal the color plays and shifts. Australia’s Lightning Ridge is known for its rare and stunning black Opals. The opal is a soft stone, a hydrated amorphous form of silica; its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Because of its amorphous character, it is classed as a mineraloid. To maintain it’s lustre, take off your opals before washing your hands. The opal is a birthsonte of October.
Pearl – Pearl is one gem that does not come from the earth. It is a gem that forms in mollusks (clams, oysters, mussels and such), which can be found in fresh and salt water. Pearls are formed when some sort of small foreign body, such as a grain of sand, or a small parasite, gets inside the mollusk and layers of pearly material form around it as a natural defense against these irritants. In a true pearl (not cultured) the layers build up like the layers of an onion, in concentric circles. Light reflecting from these overlapping layers creates a characteristic iridescent luster, also known as the orient of pearl. The older the pearl is, the more numerous the layers are, and the larger the pearl is. Real pearls are becoming more and more scarce as the waters where the pearl-producers live are becoming increasingly contaminated and many mollusk-producing areas have been partially exhausted by being overworked.
Pearls are not measured by carat; their weight is given in grains. One grain of pearl is equal to one-quarter carat of gem stone weight, so it takes 4 grains of pearl to equal 1 carat in weight of other gemstones. The colour of genuine pearls ranges from white to pink, blue, brown, gray and black, depending on the type of mollusk and the water in which they are found. Experts judge pearls by size, shape, colour, luster, and degree of perfection. Pearls rate a 2.5-4.5 on the hardness scale.
Quartz – Quartz is one of the most widely distributed minerals in the earth’s crust and one of the most common minerals on earth. Because it is so abundant, it is also affordable. Quartz is the most versatile of any of the gem families. It includes more variety and a larger number of gems than any of the other three mineral families combined. Quartz offers a variety of colour choices in both transparent and non-transparent varieties. Of the transparent types of quartz, amethyst is the most valuable. Also in the transparent group is the absolutely clear rock quartz- the kind fortune tellers’ crystal balls are made out of. Yellowish shades of quartz are called citrine. Brownish quartz is called smoky topaz. Another variety of transparent quartz is called Ametrine.
Rose Quartz is a light to dark pink variety, which was popular for many years in carved pieces such as beads, statues, ashtrays, lamp bases, and pins and brooches.
The name quartz may be derived from querkluftertz, an old German word referring to whitish vein quartz. The name has also been said to derive from the ancient Greek word krustallos, meaning, ice, because the Greeks (and the Romans) believed that quartz was ice that never melted because it was formed by the gods.
Spinel – The name spinel comes from the Greek word for spark. The name has also been said to come from the Latin word spina for spine or thorn, because spinel is often found as very sharp crystals. Since medieval times, spinel has also been known as the balas ruby, after Balascia (today Badakhshan), a region of northeast Afghanistan that for many years was a source of fine specimens of spinel. Spinel comes in many different colors however red and blue are the most famous because for centuries they have been mistaken for ruby and sapphire.
Spinel is a hard stone, rating an 8 on the hardness scale. The stone is transparent to almost opaque, has vitreous luster, and comes in many colours ranging from yellow to red to rose, green, blue or violet. Its colours are caused by various metallic impurities. Colourless spinel also exists- this is the purest form of spinel. The most popular colour of spinel is red, which is mistaken for ruby because the two gems share many of the same properties. They are similar in amount of luster, density and hardness, as well as chemical composition, deriving their red hue from chromium, though spinel actually has a slightly pinker hue than ruby.
Tsavorite – Tsavorite is an example of the fact that even nowadays, it is still possible for new gemstones to emerge onto the market. Tsavorite is a rare member of the garnet family and a new member to the jewelry market.
As it is a garnet, it is the birthstone for the month of January. Tsavorite is a rich, deep green emerald colored garnet. It was discovered in Tsavo National Park, Kenya, in 1967 by Campbell Bridges, and was introduced to the trade in the 1970’s. Tiffany’s Henry Platt, along with Campbell Bridges, coined the name tsavorite in 1974. Tsavorite looks similar to an emerald but is more brilliant and durable. Fine quality tsavorite stones over two carats are more rare than emerald, and in general, tsavorite only costs about one-tenth the price of an emerald. Because tsavorite is not very well known, there is not too much demand for the stone, as say, there is for an emerald, which is one of the reasons it is far less expensive. The gemstone is in demand more by collectors and connoisseurs, than by the general public.
Turqoise – Turquoise is a hydrated phosphate of copper and aluminum. The stone has been long prized for its intense colour, which varies from sky blue to a paler sky blue, to greenish blue, or pale green, depending on the quantities of iron and copper within it. Like other gems, the richer colour types are the most appreciated. The most preferred colour is a strong sky blue. Pale greenish blue is less highly prized and the pale green variety even less so. Turquoise’s intense blue colour is often modeled with veins of brown limonite or black manganese oxide. Turquoise with black veins is called “Spider web” turquoise. Turquoise rates a 5-6 on the hardness scale.
Laboratory-made turquoise has uniform color and no veins. The best quality turquoise still comes from Iran but in relative small quantities. Turquoise occurs in a green variety in Tibet. It is also found in various colours in the Mojave Desert of California, the Cerrillos Hills near Santa Fe, New Mexico, Arizona, Nevada, Utah and Colorado. Many of these deposits were mined centuries ago by Native Americans. Additional mines are in England, Australia, Siberia, France, Germany, Chile, Egypt, Tibet, Mexico and China.
Zircon – Zircon is the oldest mineral on earth and is found in the crust of the earth. It occurs as a common accessory mineral in igneous rocks, in metamorphic rocks and as grains in sedimentary rocks. It is a common constituent of most sands and has been used for thousands of years. Zircon is a September birthstone.
The name ‘zircon’ comes from the Persian word ‘zargun’, which means ‘gold-coloured’, although the mineral comes in a variety of colors. The colourless variety of zircon has been the most popular kind, as it is the most similar looking stone to diamond because if its brilliance and dispersion. Sadly, zircon is often confused with cubic zirconia, the laboratory grown imitation diamond, because of its similar name. As such, many people are unaware of the existence of this natural, beautiful stone.