A guide to our business model and market

A guide to our business model and market

LDE _1.19.1

(Infinity set: part of LDE's fine emerald range)

About us

We are an internationally recognised specialist bespoke jeweller and dealer of natural Colombian emeralds, sapphires, rubies and other coloured gemstones, diamonds and coloured diamonds. We are based in Hatton Garden, London's centuries' old jewellery district, and we have just opened a sales office in Istanbul, Turkey, in order to expand our customer base into the Middle East and Asia-Pacific.

Muzo mining region

(The Muzo emerald mining region)

We have access to the largest inventory of Colombian emeralds in the UK. Our emeralds are mined in the legendary Muzo region of Colombia and all come from ethical, conflict-free sources complying with UN Resolutions. We source rubies and sapphires from Burma (Myanmar), Sri Lanka (Ceylon), East Africa and Thailand. Our diamonds are supplied from the world's largest inventory of almost half a million stones around the globe. We follow a 'mine-to-market' approach and, in terms of emeralds, we are vertically integrated with Hexa Resources, our sister company, who are directly involved in exploration and mining operations in Boyacá, Colombia. This gives us a high degree of certainty when it comes to the ethics of our stones and their supply chains.


(A ring being created in our Hatton Garden workshop)

We commission bespoke jewellery in our workshop in Hatton Garden, London and we encourage our customers to visit us to meet the craftspeople who will create their jewellery by hand. We can create any item of jewellery including engagement rings, wedding rings, cocktail rings, earrings, necklaces, pendants, broaches or any other custom design. All of our gems and jewellery pieces are certified by a world-renowned gem lab. We also offer a select range of pre-made fine jewellery.

 The four C`s: Colour, Cut, Clarity, Carat

Colour – by far the most important factor in valuing a coloured gem (hue, saturation & tone). Not too dark, not too light! With emeralds the colour of a green wine bottle held to sunlight: “A fine Emerald must possess not only a pure verdant green hue, but also a high degree of transparency to be considered a top gem.” With rubies, it is Pigeon's blood red and Royal Blue for sapphires.

Muzo emerald

Pigeons blood

royal blue

Clarity – there is no such thing as a flawless emerald, however a strong hue and good clear clarity adds huge value to an emerald. Clarity can be enhanced by various treatments (which must be declared at sale and stated on the certificate). With diamonds, clarity has a more profound effect on price and the GIA grade it more precisely:


Gemstones are said to be 'eye-clean' if you cannot see any inclusions with the naked eye and 'loupe-clean' if you cannot see any inclusions under the magnification of a loupe.

Cut - Faceted = angular, cut surfaces, designed to increase the refractive qualities of the stone and its scintillation (or 'sparkle'). Cabochon = smooth, rounded surfaces.














Carat - price increases exponentially with carat size, i.e. a 2 carat stone will be worth many times more than a 1 carat stone of exactly the same clarity, cut and colour. 1 carat = 0.2 grams = the mass of a paperclip.

Diamonds are the hardest gem, at 10 on the (1-10) Moh's scale, followed by sapphires at 9 and emeralds at a much lower 7.5 (making emerald the most brittle precious stone). Consequently a 1 carat emerald can be as much as 30% larger in terms of its diamonds versus a diamond, due to its lower mass.

Some examples of notable gems that tend to increase in value over time:

  • Kashmir sapphires (last commercially mined as long ago as 1930);

  • Colombian emeralds (by far the most desirable emeralds on earth for over 500 years);

  • Burma (Mogok) rubies, spinel & sapphires;

  • Ceylan (Sri Lanka) sapphires;

  • Natural saltwater pearls;

  • Valuable jewellery pieces and gems from estate sales (especially those from high jewellers such as Van Cleef & Arpels, Boucheron, Harry Winston, Cartier, Tiffany & Co etc.)

  • Brazilian paraíba tourmaline (approaching exhaustion);

  • African ‘old mine’ ruby;

  • Russian alexandrite (mines exhausted over a century ago);

  • Cat’s eye chrysolberyl.


 When it comes to provenance, the former ownership of a gem can affect the price by as much as the region it hails from. This was most clearly demonstrated by the record $156 million achieved at the auction of Elizabeth Taylor’s fabulous collection after she passed away in 2011. However, key to establishing the physical properties, region of origin, proportions and aesthetics of a stone is its certificate. This must come from a recognised gemmological laboratory, such as the GIA (Gemmological Institute of America), Gübelin Gem Lab, Lucerne, Switzerland or SSEF (Swiss Gemmological Institute) Basel, Switzerland. Furthermore, some specialised, and slightly lesser known labs, such as CDTEC, Bogotá, Colombia (specialists in emeralds) and GCS (Gemmological Certification Services), Mayfair, London, have also built enviable reputations in their field.



Colombian emeralds are regarded as the best in the world, akin to French wine, German sports cars, Italian suits and Swiss watches! Their rich and superior green to bluish green are unparallel by emeralds from other sources. The most valuable emeralds are a slightly bluish green in a medium dark tone with strong to vivid saturation. This is the trademark colour of Colombian emeralds. The emerald mines of Muzo, Columbia, are legendary, like the Argyle for diamonds or Mogok for rubies. Muzo is the oldest emerald mine still in operation, with over five centuries of uninterrupted activity. Muzo Emeralds are prized for their size, clarity and above all, perfect colour. These characteristics make Muzo emeralds the benchmark of quality and the most sought after of all emeralds. By controlling every aspect of emerald production, from the mines through to the expert cutting and polishing, as well as the marketing of finished stones, we maintain absolute control over the quality of this product. The other significant emerald mines in Colombia are centred on Coscuez and Chivor.

Rough guidelines on emerald pricing:

Commercial emerald

Commercial Stones <$300 per carat

Accounting for more than 80% of the daily Bogotá emerald trade, these stones tend to be heavily included with little to no transparency. They will often lack colour intensity and be dull in appearance.  Commercial stones are commonly enhanced using resins which become unstable over time or when exposed to high temperature. The resin may be used to intensify colour and/or clarity meaning the true characteristics of commercial grade stones are often completely different to the final 'treated' product. Used mainly for low quality high street jewellery we do not supply commercial grade stones.

Good emerald

Good Stones $500-$1,000 per carat

These stones tend to be slightly included with perhaps a little more intensity of colour than commercial stones. Some good stones may be transparent but have little colour intensity, these stones can make attractive jewellery pieces but the fact they are generally heavily oiled to 'enhance' their appearance, or treated with resin, makes them unsuitable for any serious collector or jeweller. We do not supply 'good stones'.

Fine emerald

Fine Stones $1,000-$5,000 per carat.

These stones tend to be slightly included with perhaps a little more intensity of colour than good stones. They can make attractive jewellery pieces but they will contain 'insignificant' or 'minor' oil. We supply fine stones.

Extra Fine

Extra / Very Fine Stones >$5,000 per carat

 Comprising of around 1% of the Colombian emerald trade, these stones are always intensely and remarkably coloured with very few inclusions (and high transparency). They are un oiled, 'no-oil,' stones and therefore completely natural. No treatment of any kind is permitted. Extra Fine stones are often certified by Gübelin Gem Lab in Switzerland, widely considered to be the foremost authority on emerald analysis and grading. Extra fine Emeralds often fetch 20 times the price of a similar sized diamond and are significantly rarer, making them extremely attractive to gem collectors and investors around the world. We do supply these stones.

Education on famous emeralds:

Devonshire emerald

Devonshire Emerald

This emerald was named after the sixth Duke of Devonshire. This precious gem can now be found in a vault at the Natural History Museum in London. It is an exceptional deep green, terminated hexagonal-shaped crystal discovered in Muzo. The emerald is known as the largest and finest uncut emerald in existence and weighs a staggering 1,383.9 carats.

Patricia emerald

Patricia Emerald

This is a 630-carat, di-hexagonal cut emerald, first discovered in 1920. It is named after the mine owner's daughter, Patricia. This emerald currently resides in the American Museum of Natural History in New York.

Hooker emerald

The Hooker emerald

This is a 75.47 carat, square, inclusion-free Colombian emerald that was originally the property of Abdul Hamid II, Sultan of the Ottoman Empire. The emerald was used by the sultan to decorate a belt buckle until it was purchased by Tiffany & Co in 1911 and made into a brooch. Mrs Janet Annenberg Hooker (sister of Walter Annenberg) purchased the emerald brooch from Tiffany in 1955 and later donated it to the Smithsonian Institute in 1977.


Crown of Andes

One of the most famous pieces of Colombian emerald-encrusted jewellery in the world. It has 453 stones totalling 1,521 carats. This piece includes the 45-Carat Atahualpa Emerald, which was named after the last Inca emperor.

Photograph of the Gachala emerald (122078)

The Gachalá emerald

This is one of the most valuable and famous emeralds in the world. It was discovered in 1967 in a mine called Vega de San Juan, located in Gachalá, 142 km (88 mi) from Bogotá, Colombia. It was donated to the Smithsonian Institution by the New York jeweller, Harry Winston and now forms part of their permanent collection. At 858 carats (172 grams) it is one of the world’s largest emeralds.

 Emerald oiling: the refining process and its impact on pricing


(Image courtesy of GIA)

It is human nature to strive for excellence and this aspiration extends far beyond self-image. We strive to refine virtually everything created by mother nature, everything that is beautiful in its own natural form – including gemstones. The richer the colour and the purer the mineral the better, and this epithet is true of any gemstone. So, in pursuit of possessing nature’s treasures, the likes of which can reap great financial rewards, people began several thousand years ago to refine emeralds in a fairly simple way: oiling. To this day oil treatment is still the most common method used to enhance emeralds.

Of all the clear gem quality crystals mined across the globe, on all continents, there are few emeralds. Indeed, the highest quality green beryl stones are bestowed with complex internal crystal structures, known as the “garden-like” inclusions. In spite of the fact that a stone with attractive defects is occasionally valued no lower than its defect-free counterparts with their thick, smooth colour, we nevertheless try to correct the natural “mistakes” in the defective stone, making what seems to us to be unattractive a little less noticeable. This is achieved by gluing emeralds along possible fault lines with cedar oil or natural resin, known as “Canadian balsam”.

As far back as Ancient Egypt the process of fracture filling this wonderful gemstone has been documented in scrolls and other ancient texts. Typically the preferred method to clarity enhance an emerald is through the filling of natural fissures and fractures with natural cedar oil and Canada balsam, although other more permanent methods do exist. Unlike the treatment applied to sapphires and rubies most forms of enhancing the aesthetic appearance of an emerald are reversible.

So if oiling emeralds is only a temporary solution, why is it still the most common treatment? Because this viscous liquid has the unique property of being able to penetrate even the smallest cracks and transform into a solid substance of a nail-like nature. The varnish becomes like a sort of glue, displacing air from the cracks, dissolving debris and cementing the crystals split parts. The levels or degrees of treatment are set out by the LMHC (Lapidary Manual Harmonisation Committee) and divided into three categories: insignificant/minor, moderate and significant treatment. The stones in the first category often require a tiny amount of oil to make them reach their full potential. It may be the case that as little as one surface reaching fissure has been filled. The next - moderate degree of treatment includes stones with multiple surface reaching fissures, one or more of which will be located across the table of the emerald. The last category is comprised of stones that have multiple oil-filled fractures, many of which are surface reaching. These stones are considered by many as unsellable to retail customers.

Fracture filling

(Emerald fracture filling / oiling)

I think very few people are able to determine the type of refining an emerald has undergone, or the extent to which an emerald has been refined. Therefore, if you hope to buy stunning jewellery with a high-quality gemstone, it is best to stick with well-known brands. The green beryl jewellery in the windows of Van Cleef&Arpels, Chopard, Boucheron, Cartier and other brands of the same degree will certainly be completely natural or only improved on minimally. Over the years, gemmologists in the major jewellery houses have sought out stones for their collections and have never compromised when it came to the quality of the gem. For premium pieces of jewellery, you will have to pay the price, so if you are looking for more affordable emeralds, contact midrange boutiques or less well-known brands. They often work with emeralds refined with moderate intensity. Despite the fact that oiling emeralds makes them more visually appealing, their value suffers. If you managed to find a completely natural emerald, be prepared to pay a high price for it: these stones are so rare that we estimate they constitute a mere 0.5% of the market.

Finally, it is also worth talking about the certificates, as they are your guarantee of quality. The most respectable and reliable are the two Swiss laboratories, Gübelin and SSEF, which are involved in the inspection, analysis and documentation of the majority of Colombian emeralds on the market. However, they don’t indicate in the certificate what kind of refining process has been implemented, paying attention only to the degree of enhancement the emeralds have undergone. They refuse to specify the exact type of treatment agent not because it is impossible to identify it, but due to the fact that these laboratories will only state in writing what they can say with 100% accuracy. Missing one fissure that has been treated with a different filling material could jeopardise the laboratories’ reputation. SSEF is the only Swiss lab the gives any indication of the treatment type, classifying it as either ‘traditional’ or ‘modern.’

Regardless of the material used for oiling emeralds, it is worth remembering that the oil is highly sensitive to changes in temperature and atmospheric pressure. Therefore, if you are a frequent traveller, you should think about whether or not it is wise to always take your favourite emerald jewellery with you.


Ruby engagement ring

Rubies, along with diamonds, emeralds and sapphires, are a precious gem in high demand.  Rubies, along with their sister sapphires, are formed from the mineral corundum.  The deep red saturation of the finest rubies has long been their biggest market asset and they have the unique quality of being able to attract very high prices even with significant inclusions and in some very rare stones this can lead to the “star stone” effect.  The vast majority of rubies have undergone some form of treatment or enhancement so it is well worth understanding the effects these can have on value and to also look for stones that have been certified by a well respected laboratory.


With rubies (when considering the 4 C’s) it is the clarity and the carat that are of significantly less importance and the colour and carat size the main determiners of price. The coveted “pigeon blood red” variety from Myanmar (Burma) are by far the most sort after.  The GIA colour grading system (applied to all gemstones) recognises three characteristics: hue; tone and saturation.


Clarity relates to the transparency of a stone and any intervening objects, such as inclusions, that may influence how light is transmitted and refracted through the crystalline structure of the stone.  All corundum stones, including rubies and sapphires, are referred to as being of Type II clarity.  That is to say they usually contain inclusions within their structure.  These can exist inside the stone as a solid liquid or a gas and they can also include crystal needles of the mineral rutile, which can create a highly desirable ‘star’ effect.  The highest value stones are referred to as “loupe clean,” or VVS (Very, Very Slightly included), that is to say the inclusions themselves are not visible to the eye under 10 times magnification.  Loupe clean, stones are extremely rare, especially those above 1 carat.  Following on down the scale from these are “eye clean,” or VS (Very Small inclusion) stones with no inclusions visible to the naked human eye. SI (Small Inclusions) and I (Included) may contain inclusions that are visible to the naked eye.  Naturally value diminishes from VVS – VS – SI – I and the more inclusions, the less durable the stone may be.


Most rubies are “native cut,” that is to say they are cut and polished in or near their place of origin.  Despite the fact that the cut has the least effect on price of the 4 C’s when it come to rubies, those cuts that maximise light refraction and reflection or enhance the colour of the stone, such as step cuts, can impact the finished stone’s final value.  Emerald cuts add the most value to a ruby, followed by round, pear and marquis shapes.  Oval and cushion are the most common cuts for these stones.  Cabochon cuts can produce the much venerated “star stone” effect, if the rutile crystal inclusions are found within the stone in a conducive position.  Cabochons also carry the unique advantage of being ideal for rubies that contain inclusions that would be far too prominent for faceting.  Due to the fact that most rubies are native cut, the skills require to cut and polish these precious gemstones are highly sought after in the Western world and consequently stones cut far away from the country of origin can often be extremely expensive.


Size is critical with rubies and those stones over 1 carat are extremely rare.  As with most precious gems the price per carat of a fine ruby increases exponentially following a bell-curve which ‘jumps’ further still when a stone crosses key carats.  However some colossal rubies have been produced, including the 25.59 carat Burmese ‘Sunrise’ ruby, which fetched over $30 million at auction in 2015!

Key points to remember with rubies

  1. Red and purplish red are the colours that fetch the highest price but consider subtle variations on these to significantly lower the cost without a noticeable impact upon the visual result.

  1. It is also worth considering that small eye visible inclusions (those visible with the naked eye at 6 inches) can sometimes give the stone an aesthetic quality in its own right, far from necessarily being an undesirable factor.  The setting of the stone can also have a profound effect on the visibility of inclusions as well as the depth of the colour.

  1. Synthetic rubies have the same chemical composition as natural rubies and they have been available since the nineteenth century.  It is very hard for even a trained gemmologist to distinguish these from natural stones so certification is crucial!

  1. Unlike synthetic rubies, simulated rubies are not rubies at all, they are simply less expensive stones (such as garnet or spinel), glass or plastic adapted to appear to be rubies although they may sometimes be combined with small quantities of very low quality natural ruby.

  1. Natural rubies can be found in every continent on earth but national colour associations have built up with, for example, “Burmese” red and “Thai” red rubies gaining notoriety.  You may also come across the terms “French,” “Ceylon” or even “African” rubies but it important that these are simply marketing names and they can sometimes mislead a buyer as to the stone’s true origin.

  1. All red varieties of gem quality corundum stones are regarded as rubies and all other coloured varieties of corundum are referred to as sapphires.  However the boundaries between a pink sapphire and a ruby are not well defined or entirely agreed upon.  Rubies are rarer than sapphires so this distinction does take on an important financial consideration

  1. Heat treatment is a very common practice with rubies and it is used to remove rutile inclusions and to enhance colour tone and saturation.  Unlike coloured diamonds, this process is not dissimilar to the natural processes the stones undergo in nature so it does not have a significant effect on price.  As with other gemstones, filling fissures or fractures with polymers, resins or leaded glass will adversely affect the value of a stone.



(Duchess of Cambridge wearing Diana Princess of Wales' Kashmir sapphire engagement ring)

Sapphires have endured as one the key precious stones of choice for royalty and the well to do for many centuries but in more recent times they are becoming increasingly popular as the centre stone for engagement rings and bridal jewellery.


Sapphires are the non red variety of the mineral corundum (red corundum being a ruby) and they are most common in their blue form, although they can be found in a wide range of colours.  Besides blue, these include pink, yellow, green, orange, brown and clear.  Sapphire is the name given to a couple’s 45th wedding anniversary (the 40th belonging to her sister stone, the ruby) and it is the birthstone of the month of September.  With a Mohs’ mineral hardness of 9 (on a scale of 1-10) they are second only to diamond (which hold the benchmark score of 10).  Colour is the most important determiner of value with coloured gemstones, including sapphires.  Colour is defined by hue, tone and saturation.  A stone’s hue refers to the balance of colour in relation to its neighbours on the colour wheel and it is often measured as slight or strong.  With blue sapphires the stronger and deeper the blue the more valuable the stone.

The most desirable are defined as “royal blue,” followed by “cornflower blue,” which take their name from the fact that the cornflower is almost unique among flowers because it’s petals are pure blue, as opposed to violet or purple (as is the case with most other ‘blue’ flowers).  Tone refers to how light or dark the colour within the stone is, ranging from very light to very dark.  Once again, the darker the stone the rarer and hence more expensive it becomes.  Saturation relates to the vibrancy of the colour, covering a full spectrum from dull to pure vivid (with the finest appearance of colour).  High saturation, vivid stones without elements of brown or gray areas, referred to as extinction, fetch the highest premium. Unlike diamonds, sapphires and all other coloured gemstones do not have a fully standardised system, which can make comparison between stones more complicated.

Experienced dealers and jewellers have an eye of the most sought after stones and their advice and guidance is crucial in achieving value for money.  The Padparadscha Sapphire is a very rare pink-orange fancy sapphire from Sri Lanka and Myanmar (Burma) that can fetch over $25,000 USD per carat and it derides its name from the Sanskrit “padma raga,” meaning “lotus colour,” due to its resemblance to the lotus flower.  The larger the chromium content of a corundum, the deeper the shade of pink it will become and the distinction between a pink sapphire and a ruby is not always clear cut although in some countries, including the United States, there are some guidelines.


Truly flawless sapphires are almost non-existent and in fact a stone with no inclusions will instantly arouse suspicion that it me be synthetic or heavily treated.  All corundum contain rutile needles, known as ‘silk’ and, as with rubies, the vast majority of sapphires (some estimate over 90%) available today have been heat treated in some way shape or form.  Due to the prevalence of inclusions in sapphires, it is “eye clean” stones that tend to be the more attainable, rather than “loupe clean.”  As with rubies, some sapphires contain ‘asterisms,’ where light is reflected from the silk to form a ‘star’ shape, which can actually add value to the stone.


Unlike diamonds, there are no standardised cut for sapphires so in essence it is down to the cutter to produce the best possible shape to maximise a sapphire’s colour and clarity.  As a rule of thumb however, a well polished sapphire will be symmetrical and it will reflect and refract light in the optimum angles to give the stone the best possible account of itself.  With very light stones it is sometimes necessary to cut very deeply in order to accentuate it’s colour.  With very dark stones the opposite is true and shallower incisions can produce the best results.  In general the most desirable shapes are oval, round, cushion and emerald but a non faceted cut, such as a cabochon, can often do justice to a sapphire containing an asterism or double asterism.


Gemstones differ widely in terms of their density, a fine emerald may be as much as 30% larger in terms of its dimensions versus a diamond.  Sapphires are generally heavier than diamonds so a sapphire may appear slightly smaller than a diamond of the same carat.  Consequently it is sometimes more useful to measure a sapphire in terms of its diameter in millimetres rather than its carat; a 1 carat sapphire generally measures around 6 mm.  Always be mindful of the fact that the vast majority of sapphires have been heat treated in some way shape or form and as such it can prove difficult to determine a natural stone from a synthetic one.  Above all else, it is essential to purchase a sapphire from a reputable source and ensure that its colour is as deep as possible.

Sapphires have endured as one the key precious stones of choice for royalty and the well to do for many centuries but in more recent times they are becoming increasingly popular as the centre stone for engagement rings and bridal jewellery.  As with all things luxury celebrity endorsement has helped this rising popularity, not least as a result of Prince William’s decision to propose to Katherine Middleton with an 18 carat blue sapphire that was once in the possession of his mother Diana, Princess of Wales.

The ancient Persians of antiquity thought the earth itself rested on a giant sapphire, which accounted for the deep blue of the sky, and the early Christians believed the ten commandments were inscribed on a sapphire tablet that was so strong it would break a hammer if it was swung against it with full force!  The etymology of the word sapphire is disputed but the most likely origin is in the Hebrew word “spir,” which is referenced in the Hebrew Bible when describing blue sapphires.

Other coloured Gems

Paraiba tourmaline

(Paraíba tourmaline can fetch up to US$60,000 per carat)

These include: Paraíba tourmaline, alexandrite, morganite, golden beryl, spinel and many more beside. Paraíba tourmaline originate in Brazil and they have become one of the most desirable coloured gemstones in recent times, rivalling the price per carat of many top quality diamonds and other stones. We can source almost any coloured stone from anywhere on earth.

 Diamonds & Coloured diamonds


We have access to one of the largest inventories of wholesale diamonds in the world. Comprising more than 400,000 individual stones of every conceivable cut, colour, clarity and carat size we can find the right gem for you. By operating in a streamlined manner and only buying gemstones from the top of the supply chain, we can deliver unbeatable value. We supply GIA (Gemmological Institute of America) certified diamonds with the guarantee that our prices will not be beaten, or we will refund the difference.


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