CHOOSING A PRECIOUS GEM
Coloured gemstones are valued primarily by their colour, followed by clarity, cut, weight, origin, and treatment.
Colour is the paramount factor. It's assessed across three components: hue, which is the gem's basic colour; tone, its lightness or darkness; and saturation, the intensity of that colour.
The optimal stone has a medium-to-medium-dark tone with high saturation. Too light, and it looks washed out. Too dark, and it loses brilliance.
Provenance from a recognised source, combined with little or no treatment, significantly increases a stone's value.
PRECIOUS GEMS
Diamonds carry a legacy spanning over two millennia — from the fabled Golconda mines of India, whose legendary stones once adorned Mughal emperors, to the wild Atlantic seabed off Namibia, and the storied mining regions of Africa. The journey begins nearly 150 miles deep within the Earth's mantle, where extraordinary heat and unimaginable pressure work in silence over millions of years, transforming simple carbon into nature's hardest, most enduring crystal. It takes a dramatic act of nature — a kimberlite eruption — to carry these treasures from the depths to the surface, while others journey slowly through rivers and time, settling into alluvial deposits shaped by millennia of erosion. Every diamond, then, is not merely mined but discovered — the culmination of an ancient, elemental process, brought into the light through extraordinary skill and modern precision.
Diamond is the birthstone for April
Fancy diamonds, also known as coloured diamonds, come in a wide range of hues, from black and brown to orange, green, pink, blue, and red. Colour is graded by intensity, ranging from Fancy Light to Fancy, Fancy Intense, and finally Fancy Vivid — the rarest and most valuable grade. Most coloured diamonds show a secondary colour, such as orangey pink; those with a pure, single hue are far rarer. Coloured diamonds are mined in locations similar to those of white diamonds, including Brazil. The closure of Australia's Argyle Diamond Mine in 2020 — once the source of over 90% of the world's pink diamonds and its rare reds — created a permanent supply shock that has significantly accelerated price appreciation for natural pink and red diamonds.
Burmese rubies from the Mogok Valley, Myanmar, known as the "Valley of Rubies," where mining has been ongoing for over 2,000 years, are highly sought after. Especially those displaying a vivid red hue with strong fluorescence, known in the trade as "Pigeon Blood Red." The continually high prices of Burmese rubies are driven by the depletion of the mines and the limited supply of gem-quality stones unearthed.
Mozambique rubies from the Montepuez mine are considered an alternative to Burmese rubies. Discovered in 2009, the deposit produces stones ranging in colour from deep red to purplish or raspberry red. Compared to Burmese rubies, Mozambique material typically shows fewer visible inclusions and a cleaner overall appearance.
Ruby is the birthstone for July
Kashmir sapphires were discovered in 1881, when a landslide high in the Zanskar range of the Himalayas uncovered a deposit unlike any the world had seen. Mining began the following year, and for just six years, the "Old Mine" era of 1882 to 1887, workers pulled sapphires from that deposit before it ran dry and mining in the region effectively came to an end. That scarcity is what makes the Kashmir sapphire the most coveted sapphire of all. It's prized above all for that velvety blue, what we call cornflower blue. So when you hold a genuine Kashmir sapphire today, you're really holding a piece of that history.
Burmese sapphires from the ancient mines of Mogok are famous for their exceptional quality and intense, richly saturated colour. The finest examples display a "royal blue" hue — deep and vivid, often with a subtle violet undertone — considered among the most prized colours in the sapphire world.
Ceylon sapphires are renowned for their vivid mid-blue colour, generally lighter and brighter than sapphires from other sources worldwide. The mines of Ceylon (Sri Lanka) are also notable for producing "fancy" sapphires in pink, yellow, and purple, as well as the rare and highly prized Padparadscha — a delicate blend of pink and orange found nowhere else in such fine quality.
Sapphire is the birthstone for September
Colombian emeralds trace their legacy back centuries before the conquistadors ever set foot in the Andes — the Muisca people revered these stones long before Spain laid claim to the Muzo and Chivor mines in the 16th century. These two legendary deposits remain, to this day, the source of the finest emeralds ever brought to market. Muzo yields an intensely saturated, pure green of extraordinary depth, prized above all others for its colour purity. Chivor produces a rarer, more ethereal bluish-green, celebrated for its exceptional transparency and luminous clarity. Together, they represent the pinnacle of the emerald world — the uncontested benchmark against which every other emerald, from any origin, is measured.
Zambian emeralds account for the second-largest share of the global emerald market. They are typically more transparent, with fewer inclusions, than their Colombian counterparts and display a rich bluish-green colour, resulting from their higher iron content. Whilst not as historically celebrated as Colombian stones, they are highly regarded in the industry and increasingly valued for their clarity and colour.
Emerald is the birthstone for May
A SELECTION OF SEMI-PRECIOUS GEMS
Paraíba tourmaline is widely regarded as the most exciting gem to enter the market in the past several decades. First discovered in Brazil's Paraíba state in the late 1980s, the original deposit was small and quickly depleted by intensive mining, making genuine Brazilian Paraíba material extremely rare and highly sought after today. Later discoveries in Mozambique and Nigeria have expanded supply, with Mozambique now accounting for the large majority of material reaching the global market. What unites all three origins under the "Paraíba" name is a shared cause of colour: trace elements of copper, which produce the gem's signature vivid, neon blue-to-green hue — a saturation and glow unmatched by any other tourmaline variety.
Paraiba tourmaline is the birthstone for October
Tsavorite is a compelling alternative to emerald. Discovered in 1967 in the Simanjiro Mountains of Tanzania, with commercial mining later established near Kenya's Tsavo National Park (from which it takes its name), it offers a rich, saturated green with none of emerald's usual trade-offs — no oiling, no treatment of any kind. It also holds up well to daily wear, with clarity that compares favourably to fine emerald. This combination of natural beauty and durability has made tsavorite increasingly popular among collectors and jewellers alike.
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Tsavorite is the birthstone of January
Aquamarine takes its name from the Latin aqua marina, meaning "water of the sea", a reflection of its blue colour.
The finest aquamarines are mined in Brazil, in the provinces of Minas Gerais, Espírito Santo and Bahia, although they are also sourced in Africa and Asia. The key feature when choosing an aquamarine is colour, with mid- to dark-blue tones being the most sought-after.
Aquamarine is the birthstone for March
Tanzanite is among the rarest gemstones available today, sourced exclusively from a single location near Mount Kilimanjaro in Tanzania. First discovered in 1967, it is distinguished by a striking colour shift — moving between blue, violet, and burgundy depending on the angle of view. As no other deposit has ever been found, the world's tanzanite supply is inherently finite, a scarcity that underpins its strong appeal among collectors.
Tanzanite is the birthstone of December
Opals are true wonders of nature; their depth, colour, and movement are mesmerising. There are several distinct types: the most valuable is black opal from Lightning Ridge, Australia; fire opal, typically orange to red, from Mexico; and Welo opal from Ethiopia, where flashes of colour dance within a translucent to transparent body. The value of an opal is determined by its body tone, brightness, play-of-colour, and pattern.
Opal is the birthstone for October
TREATMENT
An estimated 95% of precious and semi-precious gems are treated to enhance their appearance; untreated gems are rare and fetch high prices. When reviewing a stone's certificate, check the treatment comment, which indicates if the stone is treated and, if so, by which process and to what extent. There are several methods for treating a gem to enhance its appearance; listed below are two widely accepted practices within the jewellery industry.
Heat Treatment. Rubies and Sapphires both undergo this process, in which the stones are heated to 800-1900 °C, dissolving internal silk and enhancing their colour. Paraiba Tourmaline also undergoes heat treatment at low to moderate temperatures to remove unwanted violet, purple, or reddish manganese hues. This stable treatment intensifies the vivid neon-blue or greenish-blue colour caused by copper.
Oiling emeralds is a traditional method that fills surface-reaching micro-fractures with colourless cedarwood oil (or similar natural oils), greatly enhancing transparency, brilliance, and colour. Since cedarwood oil has a refractive index close to that of emerald, internal flaws become almost invisible. The level of oiling is recorded on a certificate as No oil, Insignificant, Minor, Moderate, and Significant.
CERTIFICATION
Gubelin and SSEF are the two most respected in the industry for certifying rubies, emeralds, and sapphires.
The Core Focus Areas
Identity & Authenticity: Verifying the precise mineral species and ensuring the stone is natural rather than synthetic.
Geographic Origin: Tracing the provenance (such as Burmese rubies or Colombian emeralds) by analysing microscopic internal inclusions and using advanced trace-element chemical analysis.
Treatments & Enhancements: Detecting and reporting any thermal enhancements, clarity treatments, or artificial fillings (such as oil/resin in emeralds).
Gemstone Rating: Assessing high-value stones on a 100-point scale covering visual quality (colour, clarity, cut), market rarity, and salience (attractiveness and unique phenomena)
SAMPLE