A-Z directory of Gemstones

Amethyst – The Regal Purple Gem

Amethyst is the best-known purple variety of quartz and has been admired for thousands of years. Before large deposits were discovered in Brazil during the nineteenth century, fine amethyst was considered among the most valuable coloured gemstones and was often set alongside diamonds, rubies, emeralds and sapphires in royal and ecclesiastical jewellery.

Its colour ranges from delicate lilac through rich violet to deep royal purple, with the most highly prized stones displaying strong saturation and flashes of red or blue. At the paler end of the spectrum, the soft lavender-pink shades are often known as Rose de France amethyst. These subtle pastel colours became particularly popular in twentieth-century jewellery and remain highly sought after for their elegant appearance.

With a hardness of 7 on the Mohs scale, amethyst is durable enough for most jewellery, although it should still be protected from sharp knocks and prolonged exposure to strong sunlight, which may gradually fade its colour over many years. Antique examples can be found in Georgian, Victorian, Edwardian and Art Deco jewellery, where it was fashioned into everything from mourning brooches and rivière necklaces to elaborate cocktail rings.

Ammolite - Canada's Iridescent Organic Gem

Ammolite is one of the rarest and most visually spectacular gemstones in the world, formed from the fossilised shells of ammonites - ancient cephalopods that lived in the seas covering what is now North America during the Cretaceous period, some 65 to 75 million years ago. The gem quality material is found almost exclusively along the eastern slopes of the Rocky Mountains in Alberta, Canada, making it one of the few gemstones with a single, highly localised source.

The shell of the ammonite is composed of aragonite, the same mineral found in mother of pearl, and it is the microscopic layered structure of this material that produces ammolite's extraordinary optical effect. Light entering the stone is refracted and reflected between the layers, producing an intense iridescent play of colour - known as adularescence or schiller - that shifts and rotates as the stone is moved. The colour range is exceptional, vivid reds, oranges, greens, blues and purples can all appear within a single stone, with the rarest examples showing a full spectral rotation. Red and green are the most common; blue and violet are significantly rarer and command a premium.

Ammolite is relatively soft and fragile, typically measuring 3.5 to 4.5 on the Mohs scale, and most gem quality material is stabilised or capped with a protective layer of clear quartz or spinel before setting.

Commercially recognised as a gemstone only since 1981, ammolite remains little known outside collector circles, which makes well-presented examples particularly interesting for those looking for something genuinely unusual.

Aquamarine - The Sea-Blue Beryl

Aquamarine is the pale blue to blue-green variety of beryl, the same mineral family as emerald. Its name comes from the Latin aqua marina - sea water - a reference to the clear, luminous blue that characterises the finest stones. The colour is caused by traces of iron within the crystal structure, with the most prized examples showing a strong even blue with good transparency and no greenish secondary tone.

Major sources include Brazil, which produces the majority of gem quality material, along with Nigeria, Mozambique, Madagascar and Pakistan. The famous Santa Maria deposit in Brazil gave its name to a particularly intense, saturated blue that remains a benchmark for quality. Aquamarine from the Karakorum mountains of Pakistan is also highly regarded for its exceptional clarity.

With a hardness of 7.5 to 8 on the Mohs scale, aquamarine is a durable gemstone well suited to all forms of jewellery including rings intended for regular wear. Its excellent clarity - most gem quality stones are eye-clean - and the ease with which it takes a high polish make it a favourite with jewellers. It was particularly popular in the Art Deco period, where its cool, precise colour suited the geometric aesthetic of the era, and fine aquamarine pieces from this period are among the most collectable of 20th-century jewellery.

Aquamarine is the traditional birthstone for March.

Blue John – Britain's Rarest Decorative Stone

Blue John is one of Britain's most distinctive and sought-after ornamental stones, instantly recognisable by its striking bands of purple, blue and golden cream. Found almost exclusively beneath Castleton in Derbyshire, genuine Blue John is incredibly rare, with only a small amount mined each year.

Blue John is a variety of fluorite, a mineral made from calcium fluoride. Its beautiful banded appearance was created millions of years ago as mineral-rich fluids filled cracks within the surrounding limestone. Tiny changes in the mineral composition during its formation produced the unique layers of colour that make every piece different.

Unlike many gemstones, Blue John is relatively soft, measuring around 4 on the Mohs hardness scale. This means it is best suited to pendants, earrings and display pieces, while rings and bracelets should be worn with a little extra care.

For centuries, Blue John has been carved into fine jewellery, vases, bowls and decorative ornaments, with examples prized by collectors around the world. Its rarity, unmistakable colouring and rich Derbyshire heritage make it one of Britain's most treasured decorative stones, and every genuine piece tells a story that cannot be replicated anywhere else.

Chrome diopside

Chrome diopside is a vivid green gemstone variety of diopside, prized for its rich forest-green to bright emerald-green colour, caused by chromium within the crystal structure.

Technically, it sits at around 5.5 to 6 on the Mohs scale, so it is best suited to earrings, pendants and occasional-wear rings rather than hard everyday use. It can take a good polish and often has excellent transparency, giving fine stones a lively, glowing green appearance.

Chrome diopside became widely available in the late 20th century, particularly after deposits from Siberia reached the international gem market. Its intense natural colour has made it popular as an accessible alternative to emerald or tsavorite garnet, offering striking green tones without the same price level as those better known stones.

Chrysocolla – Nature’s Blue-Green Masterpiece

Chrysocolla is one of those gemstones that immediately catches the eye with its vivid mix of turquoise blues and rich greens. Often found alongside copper deposits, it has an unmistakable appearance that makes every cabochon feel like a miniature landscape or an aerial view of tropical waters. No two pieces are ever quite the same, which is a big part of its appeal.

Chrysocolla develops in the weathered zones of copper ore deposits, where copper-rich mineral solutions slowly crystallise over thousands of years. The presence of copper is what gives the gemstone its striking blue and green colours, often blended with darker matrix patterns or subtle earthy tones.

Unlike many transparent gemstones, chrysocolla is usually opaque, allowing its intricate patterns and colour variations to become the star of the piece, it is a relatively soft gemstone, typically measuring 2.5–3.5 on the Mohs hardness scale. 

Chrysocolla offers something that few gemstones can match, vibrant natural colour combined with completely unique patterns. Whether set in sterling silver or added to a mineral collection, it has an organic, artistic character that never feels mass-produced. For anyone looking for a gemstone with individuality and unmistakable natural beauty, chrysocolla is hard to overlook.

Citrine 

Citrine is a bright, warm quartz variety prized for its golden‑yellow to honey‑amber colour, caused by traces of iron within the crystal structure.

 Technically, it sits at 7 on the Mohs scale, making it durable enough for everyday jewellery while still taking an excellent polish, which is why jewellers love working with it. Its clarity, stable colour and resistance to scratching make it especially good for rings and pendants that see regular wear.

 Historically, citrine has been used since antiquity — the ancient Greeks carved it into intaglios, and it became hugely popular in the Victorian era and again in the Art Deco period, when its bold colour suited geometric designs. Today, it remains one of the most accessible and cheerful gemstones, offering the look of yellow topaz at a far more affordable price.

Diamond

Born deep within the Earth over billions of years, diamond is the hardest naturally occurring substance known. Formed under immense heat and pressure, each crystal is a remarkable testament to nature's ability to transform one of the simplest elements, carbon, into one of its most extraordinary creations.

While renowned for its brilliance once cut and polished, a rough diamond possesses a beauty all of its own. Its natural crystal faces, subtle translucency and raw, untouched form reveal the stone exactly as it emerged from the ancient rocks that concealed it for millions of years.

Diamonds have long symbolised strength, endurance and everlasting love, yet they are equally admired for their geological story. Every stone carries a history that predates humanity itself, making each specimen a unique fragment of Earth's distant past.

Whether appreciated in its natural state or fashioned into a sparkling gemstone, diamond remains one of the world's most captivating and enduring treasures.

Emerald

Emerald is the rich green variety of the mineral beryl and has been prized for more than two thousand years. Its vivid colour has made it one of the world's most desirable gemstones, with famous sources including Colombia, Zambia and Brazil. Colombian emeralds, in particular, have long been regarded as the benchmark for their exceptional colour and clarity.

The finest emeralds display a deep, vibrant green with good transparency, although most natural stones contain internal features known as inclusions. These natural characteristics are so common that they are often described as the stone's jardin (French for "garden"), and they are regarded as an important indicator of natural origin rather than a flaw. Unlike many other gemstones, a completely clean emerald may actually warrant closer examination.

With a hardness of 7.5–8 on the Mohs scale, emerald is reasonably hard but can be more fragile than its hardness suggests due to its natural inclusions. It is best protected from sharp knocks and sudden changes in temperature, and ultrasonic cleaning is generally not recommended.

Antique emerald jewellery appears in Georgian, Victorian, Edwardian and Art Deco designs, where the stone was used in everything from delicate cluster rings to elaborate brooches and pendant necklaces, its rich green colour providing a striking contrast with diamonds and pearls.

Garnet is one of the world's oldest and most recognisable gemstones, prized for its rich colours, excellent durability and fascinating history. Although most people associate garnets with a deep crimson red, this gemstone family actually occurs in almost every colour, including vibrant green, orange, pink, purple and even colour-changing varieties. Blue garnets are exceptionally rare.

The name "garnet" comes from the Latin word granatus, meaning "seed-like", as the deep red crystals were thought to resemble the seeds of a pomegranate. Garnets have been used in jewellery for over 5,000 years and were particularly popular with the Ancient Egyptians, Romans and later the Victorians, who frequently featured them in brooches, rings and lockets.

With a hardness of 6.5 to 7.5 on the Mohs scale, garnets are durable enough for everyday jewellery while still offering exceptional brilliance when expertly cut. Their high lustre and rich colour make them an excellent choice for rings, pendants, earrings and bracelets.

Most antique garnet jewellery features Almandine or Pyrope garnets, both known for their classic deep red appearance. Victorian jewellers also favoured rose-cut and cabochon garnets, often setting them in yellow gold to create a striking contrast. The famous Bohemian garnet jewellery of the 19th century remains highly sought after by collectors today.

Garnet is the traditional birthstone for January and is often associated with love, friendship and protection. Throughout history it was believed to safeguard travellers on long journeys, making it a popular gemstone to wear or gift.

Whether featured in antique Victorian jewellery or modern designs, garnets continue to be admired for their timeless beauty, excellent wearability and remarkable variety of colours.

Hematite - Iron's Metallic Mirror

Hematite is an iron oxide mineral prized for its distinctive metallic lustre and deep, near-black colour. When cut and polished, it takes on a bright, mirror-like surface that ranges from silver-grey to gunmetal black, giving finished pieces a striking, weighty appearance quite unlike any other gemstone. Despite its dark exterior, hematite's streak - the colour it leaves when scratched across an unglazed surface - is a characteristic red-brown, a reminder that it is the same mineral responsible for the red colouration of iron-rich soils and rocks worldwide.

With a hardness of 5 to 6.5 on the Mohs scale, hematite is moderately durable but can be brittle, and pieces should be protected from sharp knocks. It is a dense, heavy stone - noticeably so when handled - which contributes to the substantial feel of hematite jewellery. It is most commonly cut as cabochons, beads or flat polished pieces, and was particularly popular in Victorian mourning jewellery, where its sombre, reflective quality suited the aesthetic of the period. It was also widely used in intaglio seals and cameos, as it carves cleanly and holds fine detail well.

Hematite has been used decoratively for thousands of years - ancient Egyptians used it in amulets, and Roman soldiers wore hematite rings believing the stone offered protection in battle. In the 20th century it became popular in Art Deco jewellery for its clean, graphic contrast against silver and white metals.

Hematite is sometimes confused with marcasite in antique jewellery descriptions, though the two are distinct - marcasite is iron pyrite and has a warmer, more golden tone, while hematite is cooler and darker.

Jade - Jadeite & Nephrite

Jade is one of the most culturally significant gemstones in the world, revered across Asia for thousands of years and prized in Mesoamerican civilisations long before European contact. What most people don't know is that "jade" is not a single mineral - it is a name applied to two entirely distinct stones: jadeite and nephrite. The two look similar to the untrained eye and share a long history of use, but they differ in composition, rarity and value.

Jadeite is the rarer and generally more valuable of the two. It is a sodium aluminium silicate mineral, harder than nephrite at 6.5 to 7 on the Mohs scale, and capable of taking an exceptionally high polish. The finest jadeite - known as Imperial jade - is a vivid, even, translucent emerald green caused by traces of chromium, and stones of this quality from Myanmar (Burma) command prices that rival the finest coloured gemstones. Jadeite also occurs in lavender, white, yellow, orange and black. The term "A-jade" refers to untreated natural jadeite; "B-jade" has been polymer-impregnated to improve clarity, and "C-jade" has been dyed

Nephrite is a calcium magnesium iron silicate and the more commonly encountered of the two. It is slightly softer at 6 to 6.5 on the Mohs scale but is actually tougher than jadeite due to its interlocking fibrous crystal structure, which makes it highly resistant to fracture. Its colour range runs from creamy white - the "mutton fat" jade prized in Chinese carving traditions - through mid-greens to near-black. Nephrite sources include Canada, New Zealand (where it is known as pounamu and holds deep cultural significance for the Māori), and China.

Both forms of jade have been carved into jewellery, ritual objects, tools and decorative pieces for millennia. In Chinese culture jade carries associations with virtue, longevity and status that no other stone has matched. 

Malachite

Malachite is a copper carbonate hydroxide mineral, its vivid banded green the direct result of copper in its chemical composition. The colour ranges from pale mint through to a deep, almost black-green, and the characteristic concentric banding - formed as the mineral grows in layers around a nucleus - means no two pieces are identical. It has been used decoratively for thousands of years; the ancient Egyptians ground it for eye pigment and carved it as an amulet stone, and by the 18th and 19th centuries it was being used on a grand scale in Russia, where vast deposits in the Ural Mountains supplied the material for entire fireplace surrounds, tabletops, and the celebrated malachite room in the Winter Palace in St Petersburg.

In jewellery, malachite is typically cut en cabochon to show the banding to best effect, though it is also found carved, faceted, and as beads. It is relatively soft at 3.5-4 on the Mohs scale, which makes it susceptible to scratching and sensitive to acids - including perfume and perspiration - so pieces benefit from careful handling. The surface can be re-polished if it dulls over time.

Malachite is not a birthstone in the traditional sense, though it is widely associated with the month of May and with Taurus, and is sometimes offered as an alternative to emerald. It is also associated with the 13th wedding anniversary.

Prasiolite

Prasiolite - often called green amethyst - is a pale green variety of quartz created when heat alters the iron content within the crystal, giving it its distinctive soft, mint‑to‑sage colouring. With a hardness of 7 on the Mohs scale, it’s durable enough for everyday jewellery and takes a crisp, glassy polish, which is why jewellers enjoy cutting it into clean, modern shapes that show off its clarity. Its gentle green tone pairs beautifully with both silver and yellow gold, making it versatile for contemporary and minimalist designs.

Historically, natural prasiolite is quite rare; most material on the market began as amethyst that transformed through natural geothermal heat or controlled heating, a process known and used since the early 20th century. Today, it’s appreciated for offering an elegant, refreshing colour at an accessible price, giving jewellery a light, airy feel without sacrificing durability or sparkle.

Sapphire

Sapphire is a highly prized variety of corundum, best known for its rich blue colour, which is caused mainly by traces of iron and titanium within the crystal structure. While blue is the colour most associated with sapphire, the stone occurs in almost every colour except red - those are classified as ruby. Pink, yellow, orange, green and the rare padparadscha (a delicate salmon-pink) are all sapphire varieties in their own right.

Sitting at 9 on the Mohs scale, sapphire is one of the hardest natural gemstones used in jewellery, second only to diamond. This exceptional durability, combined with excellent brilliance and polish, makes sapphire especially suitable for engagement rings, dress rings and pieces intended for regular wear.

Historically, sapphire has been valued for thousands of years and was associated with wisdom, loyalty and protection. Fine blue sapphires from Ceylon (now Sri Lanka) have long been especially admired for their bright, lively colour. Sapphire is the traditional birthstone for September and appears throughout antique jewellery from the Georgian period onwards, most notably in the cluster and halo settings that were fashionable in the Victorian and Edwardian eras.

Smoky Quartz

Smoky quartz is a rich, atmospheric variety of quartz known for its natural brown‑to‑charcoal colouring, caused by trace aluminium in the crystal lattice exposed to natural radiation over millions of years.

Sitting at 7 on the Mohs scale, it’s a tough, reliable gemstone that handles daily wear well, making it ideal for rings, pendants and statement pieces that need both presence and durability. Its clarity ranges from transparent “whisky” tones to deep, velvety near‑black, giving jewellers huge flexibility in design - it pairs beautifully with silver for a cool, modern look, or with yellow gold for a warm, vintage feel.

Historically, smoky quartz has been used since ancient times, with notable popularity in Scotland, where “Cairngorm” smoky quartz became a hallmark of traditional Highland jewellery. Today it remains a favourite for its moody elegance, affordability and the way it brings depth and sophistication to both minimalist and bold jewellery styles.

Tiger's Eye

Tiger's Eye is one of the world's most recognisable gemstones, admired for its rich golden-brown colours and silky bands of light that appear to move across the surface as the stone is turned. This optical effect, known as chatoyancy (from the French word for "cat's eye"), is created by tiny parallel fibres within the stone reflecting light.

Despite its name, Tiger's Eye isn't actually an eye-shaped crystal. It forms when the mineral crocidolite (a fibrous blue mineral) is gradually replaced by quartz over millions of years. During this process, the original fibrous structure is preserved, giving Tiger's Eye its distinctive shimmering effect.

With a hardness of around 7 on the Mohs scale, Tiger's Eye is durable enough for everyday jewellery, making it a popular choice for rings, bracelets, pendants and beads.

Most Tiger's Eye comes from South Africa, although deposits are also found in Australia, India, Namibia and parts of the United States. Every piece is unique, with natural variations in colour ranging from honey gold to deep chocolate brown.

Combining durability, striking appearance and fascinating geology, Tiger's Eye remains a favourite among jewellery lovers and gemstone collectors alike.

Tourmaline Rutilated Quartz

Rutilated quartz with black tourmaline inclusions is one of those stones that looks dramatic before you even know what you’re looking at. Technically, it’s a variety of clear or smoky quartz that has grown around slender needles of black tourmaline (schorl), creating striking in‑stone patterns that can look like ink strokes, lightning bolts or abstract brushwork.

Because quartz sits at 7 on the Mohs scale, it’s durable enough for rings, pendants and bracelets, while the tourmaline inclusions add visual depth without compromising strength. In jewellery, it’s loved for its bold, modern look — every piece is naturally one‑of‑a‑kind, and the contrast of clear quartz with jet‑black inclusions makes it easy to pair with silver, gold or mixed‑metal designs.

Historically, rutilated and included quartzes were prized in many cultures for their “captured energy” appearance, and black tourmaline in quartz has long been associated with grounding and protection. Today, it remains a favourite for contemporary designers and collectors who want gemstones with character, texture and a story visible right under the surface.

Turquoise - The Ancient Sky Stone

Turquoise is one of the oldest gemstones in continuous use, worn and traded for more than six thousand years. Its colour - ranging from pale sky blue through vivid robin's egg to blue-green - is caused by traces of copper within the mineral structure, with iron shifting the tone toward green. The finest stones are an even, saturated blue with no visible matrix; the veining of darker host rock that runs through many natural stones is a matter of taste rather than quality, and in some traditions is actively prized.

The stone's name derives from the French pierre turquoise - Turkish stone - a reference to the trade routes through which Persian material reached Europe. Persia, now Iran, was for centuries the source of the world's most admired turquoise, mined in the mountains of Khorasan near the town of Nishapur. Persian turquoise at its finest has a pure, intense blue with minimal matrix that set the standard against which all other sources were measured. The mines at Nishapur have been worked continuously for over two thousand years and remain active today.

Afghanistan has also been a significant source for millennia, producing material that tends toward a slightly greener blue and often shows more pronounced matrix. Afghan turquoise reached ancient Egypt, Greece and Rome through the same overland trade networks that carried lapis lazuli westward, and both stones appear together in some of the earliest surviving jewellery.

The character of turquoise changed significantly in the twentieth century with the development of large-scale mining in the American Southwest. The Sleeping Beauty mine in Globe, Arizona - named for the mountain's profile rather than any mythology - became one of the most important sources of the modern era. Active from the 1970s until its closure in 2012, it produced turquoise of exceptional clarity and a clean, uniform sky blue with little to no matrix - qualities that made it immediately popular with jewellers, particularly those working in the Native American tradition. The closure of the mine has made genuine Sleeping Beauty turquoise increasingly sought after, and it now commands a significant premium over material from active sources.

With a hardness of 5 to 6 on the Mohs scale, turquoise is softer than many gemstones and requires some care - it should be kept away from chemicals, perfumes and prolonged exposure to strong light, which can alter its colour over time. Most commercial turquoise is stabilised with resin to improve durability and deepen colour; natural, untreated stones of good quality are considerably rarer and more valuable. Turquoise is the traditional birthstone for December.