Collecting gemstones is a remarkably rewarding endeavour. Here at Bijaar, we’re inundated with letters and emails from happy customers who have built up some incredible jewellery collections since we first launched in 2004. Everybody collects for different reasons, but we love that Mother Nature has seen fit to spread her beautiful, natural jewels all across the globe. Starting a collection allows us all to own something tangible and alluring from all four corners of our incredible planet.
The science of gemstones is called gemology, and you could spend the rest of your life researching just one gem and still not know everything there is to know about it. Every gemstone has a fascinating and unique history, from its formation millions of years ago to its journey from the mine to your home. We’re always aware that new customers are joining us and starting their jewellery and gemstone collections, so we wanted to put together a beginner’s guide for anyone taking their first steps into the fascinating world of gemstones, which we’re delighted to present to you here. Whether you’re new to Bijaar or are joining us for the first time, we hope you find the following information informative and interesting.



To be classed as a gemstone requires that three essential criteria are met. Each stone must be beautiful, durable and rare. Let’s explore what this means.


As the saying goes, beauty is in the eye of the beholder, so this point is somewhat subjective. Any rock that is transparent with a strong body colour will unquestionably be considered a gemstone, but there’s so much more to gems than the very cleanest and clearest stones. The marketing of perfection has somewhat skewed the true meaning of what gemstones are all about, and we work hard every day to reverse this perception. Emerald, for example, features natural inclusions that even have a name – ‘jardin’, the French for ‘garden’. These make each piece utterly unique, and we think it adds beauty rather than distorting it. Take Turquoise too, with all its wonderful, natural striations. How can these not be considered beautiful? We have a wonderful range of hundreds of different gemstones available and much prefer for our collectors to decide what they want to own by seeing it with their own eyes.


If a gem is going to spend a lifetime on your hand or in your ears, it’s going to need a bit of strength. Gemstone durability is generally measured by its hardness, using a system known as the Mohs scale, which was created by the German geologist Friedrich Mohs in 1812. In simple terms, each gem is given a score between 1 and 10, with 1 being the softest (defined as Talc) and 10 being the hardest (defined as Diamond). Mohs created his scale based on which gemstones would scratch the others on his list. Nothing but another Diamond will scratch a Diamond, which is why it heads the table. Ruby and Sapphire score a 9, so they will scratch everything else on the list, including each other, but not a Diamond. If you’re going to wear your jewellery every day, it’s best to stick to the stones higher up in the table. This is precisely why Diamonds, Rubies, Sapphires and Emeralds are considered such good stones for everyday wear, and why they are so closely associated with engagement rings. These are the defining minerals for each of the 10 levels of the scale:

  • Diamond
  • Corundum (Ruby & Sapphire)
  • Topaz
  • Quartz (Amethyst & Citrine)
  • Orthoclase
  • Apatite
  • Fluorite
  • Calcite
  • Gypsum
  • Talc



Gemstones are rare, although this can be hard to quantify as we don’t know what we haven’t yet discovered. However, no gem is easy to find. Even the big Diamond mining companies are constantly looking for new sources as their sites become depleted. The world-famous Argyle Diamond Mine is due to close at some point in 2020, and it’s not an isolated case. If you take Diamond as a base, then gemstones such as Tanzanite are thought to be about 1,000 times rarer – so for every 1,000 Diamonds that are found, only one Tanzanite is found. A rare colour change Turkish Diaspore known as Csarite is thought to be around 10,000 times rarer than a Diamond, and this mine has also been closed for over two years at the time of writing. In the case of both Argyle Diamonds and Csarite, it isn’t necessarily a lack of gems that causes the closure, but a lack of viability. The deeper the mine has to go, and the bigger it gets, the more it costs to run on a day-to-day basis. At a certain point, it becomes nonviable and has to close. Csarite? mine owners have recently announced that they’re looking at different mining techniques to get to the remaining stones, which will see the mine move from an underground tunnel to an open-pit (there’s more on mining methods later). This will almost certainly raise the costs of the gemstones they find. In conclusion, there are undoubtedly incredible deposits of gemstones lying undiscovered all over the planet. The question is, will we ever be able to get to them?


There are entire encyclopedias on the formation of individual gemstones – the process is fascinating, incredibly technical and involves more variables than we could ever list. What follows is a very simplified explanation of how some gems form.

Like a recipe for a meal, each gemstone is made up of a list of ingredients – in the case of jewels, these are elements from the periodic table. If you take Quartz as an example, it is made up of silicon and oxygen, and its formula is written as SiO2, which is also called silicon dioxide. So silicon and oxygen need to be present for Quartz to form. But Quartz in this state is not a gemstone. In fact, Quartz is the second most abundant mineral on Earth, so it definitely isn’t ticking the rarity box we discussed earlier. However, if you add in just the right amount of iron, the perfect amount of heat and an almost incomprehensible amount of time, what you’ll have is Amethyst – definitely a gemstone. If the heat is a little higher, it will result in Citrine, or tweak the iron content slightly and you’ll find Prasiolite instead. They’re all types of Quartz, but they’re all different colours and are beautiful, durable (7 on the Mohs scale) and very rare.

Take carbon. The chemical formula for this is C. Graphite and Diamond are both forms of carbon with the same chemical formula, but they look very different. The variants that make a Diamond what it is are extreme heat, tremendous pressure, and millions of years. Most, but not all gemstones feature a crystal system too – a recognised pattern in which the gemstone’s atoms bond. Diamonds form in a cubic crystal system, giving them a natural shape that looks like two four-sided pyramids stuck together at the base. As an aside, this is why the playing card shape is called Diamond too – it’s no coincidence, they’re the same thing. The requisite pressure for Diamond comes from the fact they formed around 100 miles underground. Similarly, gemstones are often found in areas that have seen significant tectonic activity, such as mountain ranges where two tectonic plates have collided over millions of years.

Similarly, the gemstones Kyanite, Andalusite and Sillimanite all share a chemical formula of Al2SiO5 but have different colours, crystal systems and even hardnesses that are all dependent on the exact pressure and temperature they formed at. We could go on, but for the sake of brevity, we’ll add that the formation of gemstones is essentially a huge coincidence, a meeting of absolutely perfect conditions stretched over a very great length of time. It’s not hyperbolic to call them miracles – they are.


Most gemstones were discovered purely by accident. We can safely assume that the earliest gems to be discovered would most likely have been found just lying on the ground, or in streams. As mentioned, many gems form in mountainous regions and natural erosion over a long period has washed away the rocks from these hidden deposits and carried the gemstones downstream, where they have been deposited on riverbanks and in the streambeds. Pearls and Amber were likely washed up on beaches and discovered lying on the sand. Once we knew they existed, the digging and diving began!

Some of the more recent gemstones find come with detailed accounts of the moment they were unearthed, such as with Tanzanite or Ethiopian Opal. But many of the world’s most celebrated stones were discovered such a long time ago that their origin stories are sadly lost to time. We can only speculate what the Ancient Egyptians made of the first Turquoise pieces, or what the Ancient Aztecs said when they first set eyes on Fire Opal. Gemstone mining itself is an old trade – Lapis Lazuli is thought to have first been mined in Afghanistan around 12,000 years ago.

Sometimes gemstones are found when mining for other minerals or precious metals. Csarite? was first found in Turkey in a working bauxite mine. Diamonds form deep in the Earth, but Peridot is also found around 100 miles underground. The deepest we’ve ever dug into the Earth is around seven-and-a-half miles, so how do we even have these two stones? Volcanic activity over the millennia has pushed the deep rocks closer to the surface. These once magmatic shafts are known as kimberlite pipes, and this is what Diamond prospectors look for. If they find Peridot, they know they’re on the right track.


There are generally three ways that gemstones are mined, although of course the size and scale of the mining operation vary significantly from mine to mine. There are substantial commercial mines with modern equipment and a large workforce right down to small artisanal miners, sometimes with as little as a single miner digging through their small claim with hand tools. Mines are found all over the world in many different countries, and certain countries are renowned for the quality of the stones they produce. Examples of this include Colombian Emerald, Sri Lankan Sapphire and Australian Opal.


Perhaps the most immediately recognisable form of mining is this method, where a vertical shaft is dug to a certain depth, and then horizontal tunnels are dug out from this central point like the spokes on a bicycle wheel. This requires the prospectors to find a ‘seam’ of gemstones, which is a layer of gem-rich material sandwiched between other layers of Earth. These seams rarely run in straight lines or stay at a uniform depth, so once one is found the job of the miners is to track the seam as it winds through the Earth underground. Seams only extend so far and will eventually run dry, and then the race is on to find another seam. This can lead to remarkably complex underground warrens of tunnels.


This method is very much a ’leave no stone unturned’ approach – literally! The mine is dug as a giant hole on the surface, so the entire pit is open to the skies, and every last piece of soil is checked for gemstones. This is often done in giant sieve-like devices that wash the dirt away until just rocks remain, which are then all manually checked by eye. Once a certain viable depth is reached, these mines often start to move across the land, filling in the hole behind them and replanting trees as they go. There have even been cases where the disturbed land has been later used to create new farmland. This method is excellent in very gem rich sites but is rather an expensive way of mining if the gemstone yield is an unknown quantity.


This is the name given to gemstones that are found in rivers and streams, including in old dried-out lake beds and stream beds. While the water may not be flowing anymore, the areas beneath the surface where it once did can harbour a trove of gemstones. It’s not unknown for prospectors to still pan for gems in running streams too.


Once gemstones have been retrieved from the ground, they need to be cut or polished before they can be set into jewellery. Opaque gemstones such as Turquoise and Agate tend to be polished into a cabochon (dome) shape. Transparent and most translucent gems tend to be cut, or ‘faceted’ to use the technical term, which involves placing a very specific pattern of flat surfaces or ‘facets’ onto the rough gem. While this has a certain intricate beauty all of its own, the actual reason this is done is to improve the way light enters the gem, is bounced around inside the gem and is then shone back out of the gem. The most known and popular cut is called the Round Brilliant Cut, which is made up of 58 facets and was perfected from centuries of trial and error by a gentleman named Marcel Tolkowsky in 1919.

If you think back to the natural shape of a Diamond, our two back-to-back four-sided pyramids, and then cut off the top third, you are left with the basic silhouette of a modern round cut. People realised a long time ago that letting more light into the top of the gem improved the colour and brightness of a gemstone, and over the centuries this was refined until Tolkowsky perfected the methodology behind the cut. It is still the basis for the Round Brilliant Cut to this day. There are many other cuts too, such as the Antique Cushion Cut and the Marquise Cut to name but two. We also welcome gemstone artists to our studios to share their own cuts, often perfected over many years, such as the QuasarCut by Glenn Lehrer and the Snowflake Cut by Rudi and Ralph Wobito. Innovative new gemstone cuts are referred to as ‘Fancy Cut’.
Faceting a gemstone improves its fire, lustre and brilliance. Fire is the splitting of white light into its constituent rainbow of colours and is famous in Diamonds, and also present in many other stones, including Sphene and Zircon. Lustre is the surface reflection of the exterior of the gem, the light that is bouncing off the stone without entering it. Brilliance is the return of light to the eye from within the gem. These three types of light interaction are what we might informally refer to as ‘sparkle’. A lapidarist does the faceting work on a cutting wheel. It takes many years to learn this art to a proficient level, and these skills are often passed down family lines. The technology that drives these cutting wheels may have improved, but the incredible skills are ancient.



Cut gemstones are then set into a jewellery design which will be made up of a precious metal. Gold is timelessly popular, particularly as there are white and rose coloured variations. Silver is also incredibly popular and costs less than gold, and platinum remains the absolute pinnacle of precious metals for jewellery. A lot of work goes into jewellery design as the finished metalwork needs to compliment the gemstones and show them at their very best. When it comes to rings, the most classic design is arguably the solitaire, which showcases a single gem as its centrepiece and is popular for engagement rings. There are other designs too, such as the cluster ring, which sets lots of gemstones close together so that their proximity to one another enhances their sparkle. Earrings, bracelets, necklaces and pendants all have their limitless variations too.


Once the jewels are set into the metalwork and the piece has had a final polish and check, the design is finished. There is now just one step left before the item can be sold – it must be hallmarked at one of the UK’s four assay offices. Hallmarking dates back to the year 1300 and has been described as the first consumer protection program. It requires that every piece of jewellery over a certain metal weight (7.78g for silver, 1g for gold and 0.5g for platinum) is stamped with a purity mark before it can legally be sold here in the UK. The mark generally takes the form of four tiny marks that will be stamped somewhere inconspicuous on your jewellery. The four marks include a makers mark, the purity of the metal, the mark of the assay office at which it was stamped and a date letter, although this last mark has been optional since 1998. Our maker’s mark is generally a G in a shield for Bijaar, and all our jewellery is hallmarked at the Birmingham assay office which uses a symbol of an anchor on its side. The date letter for 2019 is a lowercase ‘u’, and this will change to a ‘v’ on January 1st 2020.
The purity mark is simply the purity of the metal in question. For example, sterling silver is 92.5% pure silver, so the stamp is ‘925’. It’s the same with gold – 9 karat gold is 37.5% pure gold, so the mark is ‘375’, and 18 karat gold is 75% pure with a mark of ‘750’. On the topic of the word karat, the word relates to gold purity when spelt with a ‘K’ and the weight of the gemstone itself when spelt with a ‘C’. So a ring would be described as a 1 carat Diamond ring in 18 karat gold.



You’ll want to keep your jewellery looking as good as new, and the occasional bit of care and cleaning will do just the trick. Most gemstones can be washed with warm water and a mild detergent, such as washing up liquid. All you need is a soft, lint-free cloth to buff each gemstone with and you can always clean the underside with a cotton wool bud. Remembering to clean underneath the stone is as important as cleaning the top. This is because the way light interacts with each stone is changed if any of the facets are dirty, and this can make your gem look dull.

This method is safe for a good number of stones, but some need extra special care, such as Emerald, Amber and Opal. Click here for a much more detailed blog on jewellery care and cleaning. Using the right method for the right stone will keep your gemstones in top condition. When you’re not wearing your jewellery, we recommend keeping each item in a jewellery box or soft pouch. As mentioned earlier, certain gemstones can scratch others, so they need to be kept in separate pouches or a jewellery box that holds each piece firmly. We sell a full range of jewellery boxes here, which you can browse online by going to this page.


We’ve only touched on the very basics of gemstones and jewellery in this feature, but before we run out of space, we have to squeeze in these incredible phenomena that certain gems display.



Some gemstones will change colour when they’re viewed in different types of light. This happens because the gemstones absorb different wavelengths of light depending on the kind of light – such as sunlight and candlelight. Alexandrite looks a deep forest green in daylight but will often appear almost Ruby red by candlelight. Csarite® has a beautiful olive green hue in sunlight but shows flashes of pink and champagne under candlelight. There are varieties of Sapphire, Fluorite and Garnet that also change in this way – it is a phenomenal sight to see.


The gemstone Kunzite will absorb sunlight and radiate, or glow, with this light for a time after it has been taken back indoors. You may be familiar with phosphorescent materials as they are used on everything from watch faces, children’s toys and fire exit signs so that they continue to glow once the light source has been removed.


Remember we talked about cabochon cuts above – when a gemstone is polished into a dome? Certain gemstones have formed in such a way that there are fibrous inclusions that, when a gemstone is polished in the right way, will reflect a sharp beam of light out of the gem. When this beam is a single line across the surface of the stone, it is known as ‘chatoyancy’, or the ‘cat’s eye’ effect. The gemstone Tiger’s Eye Quartz is known for and named after this effect. Sometimes, this beam of light will create a glorious star on the surface of the gemstone instead, which is known as ‘asterism’ or the ‘star’ effect. Star Rubies and Star Sapphires are famous for this.


To give you a starting point for what’s out there, we’ve picked some of the better-known stones and included a vast array of different colours for you to explore. If you own all of these stones you will never be short of the perfect jewellery to wear for every occasion.

The most famous gem of them all? Almost certainly, and all thanks to its remarkable fire, effortless brilliance and clarity to die for. Essential.

There are many beautiful red gemstones, and Ruby is the king of them all. A deep, vibrant red with pink undertones makes this a must-have.

Mined for thousands of years, Sapphire features a delicious deep cornflower blue hue. Other colours exist too and are known as ‘Fancy Sapphires’.

It has been said that nothing green is greener than Emerald, and its ‘jardin’ inclusions help to make each piece unique, like a fingerprint from Mother Nature.

For centuries, this regal purple stone was the reserve of kings, popes and the very wealthiest of society. A gorgeous gem with a fascinating history.

Only discovered in 1967, supplies of this intense indigo stone are running out fast, and it has been predicted to run out within our generation.

It’s hard to think of a more timelessly elegant gemstone than a Pearl, and a necklace featuring this oceanic treasure is a must-have.

This light, bright blue beauty has long been associated with the sea and was once carried by sailors as a good luck talisman.

This delightful stone is perfect for those who love a rainbow of hues as the finest specimens are full of flashes featuring all the colours you could want.

Famously a deep red, dark-toned stone, Garnet has also been discovered in a plethora of colours including green, orange and yellow.

Fossilised tree sap from ancient rainforests. Amber is often found along the beaches of the southeast of England where it washes up after a very long journey.

A bright, golden green treasure that is often found as a result of volcanic activity. There’s a green beach in Hawaii caused by the Peridot in the rocks!

Tourmaline is the true gemstone of the rainbow, with almost every hue having been discovered. They work beautifully together in clusters.

Another beautiful stone is known predominantly for its red variety, Spinel also comes in a beautiful array of dark purples, blues and pinks.

Available from light buttery yellows to deep golden cognac tones, Citrine is what happens to Amethyst when it is heated.

Often confused with Cubic Zirconia, which is a fake stone, Zircon is a natural, fiery gem that is also available in many different colours and tones.

This colour changing miracle was first discovered in Russia in 1830. The original mine has long since been depleted, but we still source a variety from India.

This soft pink jewel is the epitome of feminine grace, a perfect balance of light pastel tones and deeper pink flashes. It’s phosphorescent too.

Traditionally found either colourless or in imperial yellow hues, recent advancements in technology have allowed us to bring you Topaz in a variety of fantastic colours.

This opaque greeny-blue stunner often has unusual, natural patterns running through it, and is so famous it has a colour named after it.

We hope this feature has given you a brief but interesting overview of the jewellery and gemstone world. There’s so much more to learn, and every day we strive to bring you fascinating insight on the gemstones we source and sell, both during our blog. To learn more about jewellery and gemstones, stay tuned to Bijaar and also have a look at the rest of our blogs for many more in-depth articles.