Top 10 Most Valuable Gemstones (Rarity & Price per Carat)

The following gemstones are ranked as the most valuable in the world based on their extreme rarity and record-breaking price per carat. These are gems typically only accessible to super-millionaires and billionaires, often changing hands at exclusive auctions or high-end private sales.

1. Blue Diamond

Description (Colour & Composition): Blue diamonds are fancy-coloured diamonds (crystallized carbon) with a captivating blue hue caused by trace amounts of boron within their crystal lattice. They range from steel blue to vivid deep blue; a famed example is the 45.5 ct Hope Diamond, a rare fancy dark greyish-blue diamond. Blue diamonds are Type IIb diamonds (boron-bearing), which absorb red light and impart blue colouration. They exhibit adamantine lustre and exceptional hardness (10 on the Mohs scale), like all diamonds. Due to their extraordinary colour and clarity, blue diamonds are considered among the most stunning and coveted gems on the planet.
Value (Price per Carat): Blue diamonds command the highest prices of any gemstone, reaching around $3.9 million per carat for the finest specimens. The 14.62 ct Oppenheimer Blue set a world record when it sold for $57.5 million in 2016 (about $3.93 million per carat). In 2022, another fancy vivid blue, the 15 ct De Beers Cullinan Blue, fetched $57.4 million, underscoring the sky-high value of top blue diamonds. Only a handful of blue diamonds above 10 carats exist, and even mid-sized stones (5–10 ct) can easily surpass tens of millions in value due to intense collector demand.
Primary Sources: The premier source for blue diamonds today is the Cullinan Mine in South Africa, which has produced legendary blues (including the Blue Moon and De Beers Blue). Historically, a few came from India’s Golconda region (e.g. the Hope Diamond originated in India in the 17th century). Minor occurrences have been in Australia (the Argyle mine yielded a rare few greyish-blue stones) and Indonesia, but natural blue diamonds are exceptionally scarce worldwide. At Cullinan, for example, blue diamonds make up well under 0.1% of diamonds mined in a year. Their rarity in nature contributes directly to their immense per-carat price.
Acquisition: Ultra-wealthy buyers obtain blue diamonds through elite auction houses and top jewellers. Record-setting sales occur at Christie’s and Sotheby’s auctions – for instance, Christie’s Geneva sold the Oppenheimer Blue to a private collector. High-end jewellery houses (Graff, Harry Winston, etc.) also specialize in rare blue diamonds, often purchasing them at auction and then reselling them to clients. Many blue diamonds are ultimately traded via private treaty sales brokered by specialized dealers, given their value. These gems are so prized that some end up in museum collections (the Hope Diamond resides in the Smithsonian) or secured in the investment portfolios of billionaires.

2. Jadeite Jade

Description (Colour & Composition): Jadeite is the most precious form of jade, a pyroxene mineral (NaAlSi₂O₆) prized for its vivid green colour and translucency. The top “Imperial Jadeite” displays an emerald-green hue with a high degree of transparency and a smooth, waxy lustre. Jadeite can also occur in lavender, white, orange, or other colours, but rich green jadeite is by far the most valuable. It is a tough polycrystalline gemstone (hardness ~6.5–7) often cut into cabochons, beads, or intricate carvings. Culturally, jadeite has been treasured in China and Mesoamerica for millennia—esteemed not only for beauty but as a symbol of status and spiritual significance.
Value (Price per Carat): Top-grade jadeite is one of the world’s costliest gems, with fine pieces reaching around $3 million per carat in value. Unlike faceted gems, jadeite is usually traded per piece rather than per carat, but record sales illustrate its price: the famed Hutton-Mdivani jadeite necklace of 27 beads sold for $27.4 million at Sotheby’s in 2014 (about $1 million per bead, each bead ~15–20 mm). An exceptional jadeite cabochon ring can easily fetch millions. Jadeite’s value hinges on its colour (pure intense green), translucency, texture, and craftsmanship. Top imperial jade, virtually “emerald green glass” in appearance, inspires frenzied demand among collectors, especially in Asian markets.
Primary Sources: Almost all high-quality jadeite comes from northern Myanmar (Burma), specifically the Hpakant mines in Kachin State. Burma’s jadeite tract has produced the finest imperial jade for centuries. Historically, Burmese jade was traded with China, where it became imperial treasure. Small quantities of jadeite of lesser quality are found in Guatemala and California, but those pale in comparison to Burmese material. The Myanmar supply is limited, and mining conditions are challenging, which, combined with geopolitical factors, keeps fine jadeite extremely rare on the open market.
Acquisition: Super-rich collectors typically acquire top jadeite at auction in Hong Kong, where demand is highest. Sotheby’s and Christie’s Hong Kong sales often feature jadeite jewels as marquee lots (the Hutton-Mdivani necklace was bought by Cartier’s Collection at Sotheby’s). High-end Asian jewellery boutiques (like Chow Tai Fook or Cartier’s estate department) also handle superb jadeite, often selling privately to elite clients. Because jadeite value is judged on beauty and provenance more than weight, collectors will pay a premium for pieces with imperial pedigrees. Private transactions arranged by jade dealers are common, as billionaire buyers in China and elsewhere vie for the finest jadeite treasures outside the public eye.

3. Red Diamond

Description (Colour & Composition): Red diamonds are the rarest natural colour diamonds, composed of pure carbon but exhibiting a reddish hue due to unique lattice distortions. Unlike most fancy colours (which come from impurities), the red colour in diamonds is caused by minute defects in the crystal structure (plastic deformation) that selectively transmit red light. These diamonds range from purplish-red to brownish-red; true blood-red examples are exceedingly scarce (often graded as Fancy Vivid Red or Fancy Intense Pink-Red if slightly lighter). They are typically small – most red diamonds are under 1 carat – but they share the adamantine sparkle and hardness (10 Mohs) of colourless diamonds. A red diamond in fine quality appears as a glowing ember-like stone, and it’s often cut into shapes (radiant, oval, etc.) that enhance the depth of colour.
Value (Price per Carat): Red diamonds top the price charts, often selling for $1 million to $2 million+ per carat in the rare instances they trade. In fact, some gem experts note that red diamonds, if larger than a carat, could surpass all other gems in value per carat due to demand and rarity. The 5.11 ct Moussaieff Red Diamond (the largest known red) reportedly sold for around $8 million (early 2000s) – over $1.5M per carat – and would be worth considerably more today. Tiny 0.5 ct red diamonds from Australia’s Argyle mine have been bid to over $2 million at tender, implying $4 million+ per carat for top reds. The extreme rarity means pricing is somewhat notional; any gem-grade red diamond hitting the market sets its own record, with collectors willing to pay whatever it takes to obtain one.
Primary Sources: The Argyle Mine in Western Australia (recently closed in 2020) was famous for producing the majority of the world’s red diamonds – albeit in minute quantities (perhaps one red for every million carats of output). Most Argyle reds were under 0.5 ct and came from the mine’s annual “Tender” of top pinks/reds. A few red diamonds have also been found in Brazil (the 0.95 ct Hancock Red came from Brazil) and in Guyana and South Africa, but these occurrences are extraordinarily rare. In total, experts estimate that fewer than 30 true gem-quality red diamonds have ever been discovered. With Argyle’s closure, new red diamonds entering the market are virtually nil, making existing stones all the more valuable.
Acquisition: Only a select handful of buyers worldwide have ever acquired a red diamond. Many were originally sold through Rio Tinto’s confidential Argyle Tender to invited collectors and luxury jewelers. Today, reds trade via ultra-private sales – for example, the Moussaieff Red (formerly the “Red Shield”) was acquired by Moussaieff Jewelers from a private dealer and is occasionally exhibited. Auction appearances are extremely rare; a notable one was a 0.95 ct Fancy Purplish-Red that sold for $2 million at Christie’s in 1987 (the Hancock Red). Typically, billionaires obtain red diamonds through top diamond brokers or by networking with existing owners. High-end jewelers like Moussaieff and Graff have handled red diamonds for their clients. Given the cult status of red diamonds, collectors often hold them for decades, so any opportunity to buy one is met with fervent competition among the ultra-wealthy.

4. Blue Garnet (Colour-Change Garnet)

Description (Colour & Composition): Blue garnet is an exceptionally rare variety of garnet that can appear blue or blue-green in daylight and change to purple or red under incandescent light. These are a type of colour-change garnet rich in vanadium (often a mix of pyrope-spessartine garnet). In natural sunlight, the gem shows a teal to greenish-blue colour – an unusual hue for garnet – and under warm indoor lighting, it shifts to violet or purplish-red (similar to alexandrite’s behaviour). Chemically, they have a complex formula ((Mg,Fe,Ca)_3(Al,Fe)2Si_3O{12}) with trace vanadium or chromium causing the colour change. Blue garnets are typically transparent to translucent and can have decent hardness (~7 to 7.5 Mohs). Given their rarity, they are usually cut into smaller faceted stones when found. The phenomenon of a truly blue garnet was unheard of until their discovery in the late 1990s, astonishing gemologists with a garnet that spans the colour spectrum.
Value (Price per Carat): Blue garnet is so rare that its price per carat rivals the top diamonds. The first significant specimen was a 4.2 ct stone that sold for $6.8 million in 2003, roughly $1.5 million per carat. This places blue garnet among the most expensive gems on a per-carat basis. Typical smaller blue garnets (if you can find one) are valued in the high five to six figures per carat. The combination of a striking colour change and extreme rarity drives the price. There is effectively no “market” price, as each stone is unique. Collectors have paid over $1M for sub-1-carat gems of top quality. In summary, a fine blue garnet can easily exceed $1 million/ct and remains more expensive per carat than even most rubies or emeralds, making it a true gemological rarity for those able to obtain one.
Primary Sources: Blue colour-change garnets have only been found in a few locations. The initial discovery was in Madagascar in the late 1990s, which yielded several small blue-green garnets. Subsequent finds occurred in the Bekily area of Madagascar and a few stones in the United States (Idaho), Turkey, and Russia. These deposits are not large – only sporadic grains or crystals have surfaced. In Madagascar, the material is a mix of pyrope-spessartine with vanadium and similar materials were later identified in Oregon (USA) and Mozambique. To date, Madagascar remains the most noted source for blue garnet. The garnets are exceptionally scarce even from these sources – often only found during specialized mineral surveying. No active mine is dedicated to blue garnet; they are serendipitous finds in alluvial deposits that also produce other garnet types.
Acquisition: Given their extreme rarity, blue garnets are typically traded privately among collectors and via specialized gem dealers. Auction appearances are virtually unheard of – most collectors have never seen a blue garnet in person. The 4.2 ct specimen that sold for $6.8M was reportedly brokered between private parties (its existence was later publicized in gem journals). A few high-end dealers in coloured stones might handle a blue garnet if one becomes available, offering them quietly to top clients. Ultra-wealthy gem enthusiasts (and some museums) keep watch for any blue garnet discovery. Essentially, acquiring a blue garnet requires deep connections in the gem trade and readiness to pay a fortune. This gem doesn’t regularly show up at Christie’s or Sotheby’s; instead, billionaire collectors snap up the rare examples as soon as they are found. In recent years, a couple of colour-change garnets with strong blue hues have surfaced at boutique dealers, and they were swiftly sold into private collections at record prices.

5. Pink Diamond

Description (Colour & Composition): Pink diamonds are fancy-coloured diamonds known for their delicate pink to vivid magenta hues. Like other diamonds, they are pure carbon in composition, with the pink colour believed to result from structural distortions in the crystal lattice (and possibly trace nitrogen in some cases). They range in tone from faint blush pink to intense purplish pink; the most saturated are graded Fancy Vivid Pink. Pink diamonds often have Type IIa chemistry (very pure with no nitrogen) if from certain sources like Argyle or Type Ia if a different cause of colour. They share diamonds’ exceptional hardness and brilliance, making them dazzling in jewellery. Large pink diamonds are quite rare; most are under 5 carats, though a few notable exceptions exist. Their romantic colour and rarity have made them some of the most sought-after coloured diamonds in the world.
Value (Price per Carat): Top pink diamonds regularly exceed $1 million per carat at auction. The 59.6 ct CTF Pink Star holds the auction record for any gemstone: it sold for $71.2 million in 2017, about $1.19 million per carat. More recently, in 2022, the 11.15 ct Williamson Pink Star fetched ~$57.7 million (nearly $5.2M per carat, a record per carat for a pink). High-quality pinks of a few carats routinely sell in the tens of millions – for example, an 18.96 ct Fancy Vivid Pink (“Pink Legacy”) sold for $50 million in 2018 (≈$2.6M/ct). Even smaller 1–2 carat vivid pink diamonds from the Argyle mine have commanded $500,000 to $1,000,000 per carat in the final Argyle Tender sales. Fine pink diamonds are thus among the costliest gems, second only to the likes of blue or red diamonds in per-carat price.
Primary Sources: The most significant source of pink diamonds in modern times was the Argyle Mine in Australia, which accounted for over 90% of the world’s pink diamond supply during its operation. Argyle pinks tend to be richly coloured (often with a slight brownish or purplish modifier) and are generally small in size. Since Argyle’s 2020 closure, pinks have become even rarer. Other sources include South Africa (mines like Williamson in Tanzania produced the original 23 ct Williamson Pink given to Queen Elizabeth II) and India’s historical Golconda region (the famous Daria-i-Noor is a pale pink from India). A few pink diamonds have come from Brazil, Russia, and Canada’s Victor mine, but in very limited numbers. Overall, pink diamonds represent far less than 0.1% of all diamonds mined. The Argyle mine’s yearly output of quality pinks could literally fit in the palm of one hand, highlighting just how scarce they are.
Acquisition: Elite auctions and tenders have been the primary route for acquiring notable pink diamonds. Sotheby’s and Christie’s frequently feature important pink diamonds – for instance, the Pink Star (71.2M) and Graff Pink (46M) at Sotheby’s or the Winston Pink Legacy at Christie’s. During Argyle’s operation, the mine’s annual Pink Tender was an invitation-only silent auction where collectors and high-end jewellers bid millions for a handful of top Argyle pinks. Today, with Argyle closed, existing pink diamonds often trade hands via private sales brokered by major diamond dealers (e.g., Sotheby’s Diamonds, Christie’s Private Sales, or firms like Graff). High-end jewellery retailers such as Harry Winston, Graff, and Moussaieff have sometimes acquired big pink diamonds at auction and then sold them to their ultra-wealthy clients. In short, super-rich buyers can find pink diamonds at major auction house sales, from specialized diamond brokers, or occasionally in the bespoke collections of luxury jewellers. Each significant sale of a pink diamond tends to make headlines, given the prices involved.

6. Ruby (Burmese “Pigeon Blood” Ruby)

Description (Colour & Composition): Ruby is the red variety of corundum (Al₂O₃) and has been called the “King of Gemstones” for its rich colour and historical allure. The finest rubies exhibit a vibrant red to slightly purplish-red hue, often referred to as “pigeon blood red,” with vivid saturation and a medium-dark tone. Chromium impurities in the crystal give ruby its red colour (and cause fluorescence that can make the gem appear to glow). Rubies have a hardness of 9 (second only to diamond), excellent toughness, and a high refractive index that gives well-cut stones a brilliant sparkle. Top-quality rubies are often very clean, but most contain some needle-like inclusions (“silk”), which can soften the colour and create a desirable glow. Large rubies with fine colour are extremely rare – a top-quality ruby above 5 carats is a world-class gem. Throughout history, ruby’s blood-red colour has symbolized passion, power, and wealth, making it one of the most celebrated gems.
Value (Price per Carat): Fine rubies consistently achieve hundreds of thousands to over a million dollars per carat. The 25.59 ct Sunrise Ruby holds the record for a ruby, selling for $30.3 million in 2015 – roughly $1.18 million per carat. In 2023, a monumental 55.22 ct ruby (the “Estrela de Fura”) from Mozambique sold for $34.8 million (about $630k/ct), reflecting how even slightly lower colour saturation still commands huge prices. Top Burmese rubies of 3–5 ct routinely sell for over $200k per carat, and anything above 10 ct of top colour can easily top $1M/ct at auction. Ruby prices are driven by the 4Cs, but the colour is paramount – a truly top-colour (vivid red) ruby can be double the price of a slightly less saturated one. Untreated “pigeon blood” rubies from Myanmar, in particular, draw the highest premiums. Among all coloured gemstones apart from fancy diamonds, ruby holds the crown for the highest per-carat price.
Primary Sources: The Mogok Valley in Myanmar (Burma) has historically produced the world’s finest rubies, including the most famed “pigeon blood” gems. Burmese rubies, known for their intense red fluorescence and purity of colour, set the standard for quality. Another significant source today is Mozambique (Montepuez mine), which, since 2009 has yielded numerous high-quality rubies, including very large sizes. While many Mozambique rubies have superb clarity and size, they can have a touch of purple or pink modifier compared to Burmese stones. Other ruby sources include Thailand (darker garnet-like reds, mostly mined out), Vietnam (pinkish-red rubies from Luc Yen), Tajikistan, and Sri Lanka (often lighter “ruby-lite” stones on the pink sapphire spectrum). In recent decades Mozambique has become the volume leader in fine rubies, but Burmese rubies from Mogok and Mong Hsu are still considered the most coveted top colour. Due to their rarity and politically and geographically limited occurrence, the supply of premier rubies is very restricted.
Acquisition: High-end auctions are a primary venue for important rubies – Sotheby’s and Christie’s have set multiple ruby records (the Sunrise Ruby was sold by Sotheby’s Geneva). Collectors also acquire fine rubies through elite jewellers: names like Cartier, Van Cleef & Arpels, Bulgari, and Graff often have exceptional ruby pieces in their collections (the Sunrise Ruby was mounted by Cartier, for example). Bangkok and Geneva are key trading centres – in Bangkok’s gemstone market, ultra-rich buyers quietly buy top rubies through brokers. Private sale is common, with dealers sourcing rare rubies from miners and middlemen, then offering them to known collectors or brands. Given the demand, auctions for ruby tend to see fierce bidding, often from Asian collectors who value ruby’s cultural significance. Some of the finest Burmese rubies reside in royal treasuries and are thus off-market, so when a top ruby does become available, billionaires and luxury firms move quickly to acquire it. In summary, wealthy buyers find rubies at major auctions, through luxe jewellers (who often bid at those auctions themselves), or via specialized gem dealers in hubs like Geneva, Hong Kong, and Bangkok.

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7. Emerald (Colombian Emerald)

Description (Colour & Composition): Emerald is the green variety of beryl (Be₃Al₂Si₆O₁₈), coloured by trace amounts of chromium and/or vanadium. The finest emeralds display a vivid bluish-green to pure green colour with medium-dark tone and strong saturation – often described as “jungly” or “grass-green.” They typically form in hydrothermal veins, which means most emeralds contain inclusions (garden-like patterns or tiny crystals) that are accepted as part of the stone’s character (the French even call them jardin, or garden). Emerald has a hardness of 7.5–8, but due to inclusions, can be somewhat brittle. They are often cut as elegant emerald cuts or ovals to maximize colour while protecting the stone. Top-quality emeralds have a richly transparent green “glow” that has been cherished since antiquity – Cleopatra famously adored emeralds. A truly clean, large emerald with top colour is one of the rarest sights in nature.
Value (Price per Carat): Fine emeralds can command astounding prices, though generally a bit less per carat than rubies or diamonds. An 18.04 ct superb Colombian emerald (the Rockefeller Emerald) sold for $5.5 million, which is about $305,000 per carat. This illustrates that top emeralds easily reach six figures per carat. In another example, a smaller 1.1 ct vivid Colombian emerald of exceptional quality might be valued around $10k/ct – but the price per carat jumps exponentially with size and quality. Auction records include the 23.46 ct Smithsonian emerald (untreated) appraised around $100k/ct and Elizabeth Taylor’s 7.45 ct emerald pendant that sold for $280k/ct. It’s not uncommon for premium Colombian emeralds in the 5–10 ct range with top colour and clarity to fetch $50,000–$100,000 per carat. Emerald prices also depend on treatment: untreated stones are worth far more. While emerald’s per-carat record ($305k) is lower than ruby or diamond records, the stone’s allure and high unit value firmly place it among the most valuable gems.
Primary Sources: The most celebrated emeralds come from Colombia, specifically the Muzo, Chivor, and Coscuez mining areas in the Andes. Colombian emeralds are famed for their deeply saturated green with a hint of blue and excellent transparency. Other important sources are Zambia (e.g. Kagem mine) – Zambian emeralds tend to be a bit darker with a blue-green cast, and can be very high clarity. Brazil produces a steady supply of emeralds (often lighter colour), and Afghanistan and Pakistan have yielded fine emeralds from the Hindu Kush (high clarity, slightly more bluish green). Historically, Egypt (Cleopatra’s Mines) and Austria (Habachtal) were sources, but those are long depleted. In recent decades, Colombia has remained king for top quality, while Zambia provides a number of good stones. Notably, the largest fine emeralds in recent times – such as the 5,655 ct “Inkalamu” lion emerald (unearthed in Zambia) – show that Africa can produce giant crystals. Still, for truly top colour in the high-end market, “Colombian” is the gold standard, and such stones, especially if untreated, are exceptionally rare.
Acquisition: High-end jewellers and auctions are primary avenues for acquiring investment-grade emeralds. Christie’s and Sotheby’s often feature historic emeralds – for example, the Rockefeller Emerald was sold at Christie’s New York. Sotheby’s Geneva auctioned a 75.6 ct emerald from Catherine the Great’s collection for $4.5M. Top jewellery houses (Cartier, Bulgari, Harry Winston) have sourced important emeralds for their creations – Elizabeth Taylor’s famed emerald suite by Bulgari (comprised of top Colombian stones) sold for an astounding $24.8M in 2011. Ultra-wealthy buyers also work with specialized gem dealers in Bogota, London, or New York who handle fine emeralds. Due to treatments (like oiling) being common in emeralds, savvy collectors insist on reputable lab certification when buying at this level. Private sales are quite common: many large emeralds trade discreetly between dealers and collectors rather than at public auction. Whether at auction or private sale, billionaire collectors from around the world – especially in the Middle East and Asia – eagerly vie for the chance to own a legendary emerald with perfect colour.

8. Alexandrite

Description (Colour & Composition): Alexandrite is the rare colour-change variety of the mineral chrysoberyl (BeAl₂O₄), famed for appearing green in daylight and red in incandescent light. Often described as “emerald by day, ruby by night,” a fine alexandrite has a vivid bluish-green to teal colour in sunlight and shifts to a purplish-red or raspberry colour under warm indoor light. This remarkable optical phenomenon is due to chromium impurities, which cause different light absorption depending on the light source. Alexandrite has a hardness of 8.5, is excellent for jewelry, and is typically found in sizes under 5 carats. Most crystals are tabular or oval in shape and are cut to maximize the colour change (often as mixed cuts or cushion shapes). The gem was first discovered in Russia’s Ural Mountains in 1833 and named after Tsar Alexander II. High-quality alexandrite shows not just a colour shift but a dramatic 100% colour change from green to red. That chameleon-like nature, combined with scarcity, makes alexandrite one of the most coveted gemstones among collectors.
Value (Price per Carat): Alexandrite is extremely valuable, especially in larger sizes with strong colour changes. Small alexandrites under 1 carat can range from a few thousand to ~$15,000 per carat for good quality. However, fine stones of 2–3 carats can reach $50,000+ per carat, and gems above 5 carats in top quality have sold for over $100,000 per carat. For example, a 21.41 ct Russian alexandrite sold at Christie’s in 2017 for around $15 million (well over $700k/ct). More routinely, a top 3 ct stone might be priced around $70k/ct in today’s market. The record per-carat prices rival those of emeralds and sapphires. The dramatic increase in per-carat price with size reflects how exponentially rare larger alexandrites are. Even stones with moderate colour change (say 70% green to red shift) command high prices if they are clean and over 5 carats. Due to limited supply and high demand from connoisseurs, alexandrite remains one of the most expensive gems, easily reaching six figures per carat for the very best material.
Primary Sources: The classic source is the Ural Mountains in Russia, specifically the Tokovaya region, where alexandrite was first discovered. 19th-century Russian alexandrites set the quality benchmark (often with beautiful teal-green to purplish-red change), but those deposits were largely exhausted by the early 20th century. In the last few decades, significant deposits have been found in Sri Lanka (usually lighter green to brownish-red change), Brazil (Hemisérgio and Nova Era mines – stones tend to be larger but with bluish-green to purplish change), and Tanzania (Lake Manyara – smaller sizes, decent colour). India (Andhra Pradesh) and Madagascar have also produced some alexandrite. Today, Brazil and Sri Lanka are the primary sources for new material, though fine quality stones are rare from these. The Russian material remains the most prized when it can be found on the secondary market. In summary, alexandrite is sourced from a handful of locales worldwide, each producing only sporadic quantities. No single mine today produces a steady stream of fine alexandrite; most are byproducts of mining for other gems like chrysoberyl or emerald. This scarcity of supply contributes to its high value.
Acquisition: Collectors and high-end dealers are the main players in the alexandrite market. Large auction houses occasionally feature important alexandrites – for instance, Christie’s has sold a few notable estate pieces containing big alexandrites. However, alexandrite often finds its way to buyers through specialized gem dealers who cater to collectors. In trade centres like Geneva, Bangkok, and New York, top dealers keep lists of clients seeking alexandrites and alert them when a fine stone becomes available. Ultra-wealthy buyers may also acquire alexandrite as part of vintage jewellery from period jewellers like Fabergé or Tiffany (which used Russian alexandrites in the late 1800s). Exclusive gemstone fairs and shows (e.g. the Tucson gem show, Baselworld) sometimes see private sales of high-end alexandrites. Because fine alexandrites are so scarce, collectors are usually prepared to act fast – a single phone call from a dealer might place a gem into a billionaire’s hands before it ever reaches any public listing. Thus, while auctions are a route, private transactions dominate this market. High-end jewelers (like Bvlgari or Cartier) on occasion obtain alexandrites for bespoke pieces, but typically they source them via the same network of gem dealers. In short, to acquire a top alexandrite, one needs connections to the upper echelon of the gem trade or to keep a sharp eye on the few auction offerings that appear.

9. Musgravite

Description (Colour & Composition): Musgravite is an ultra-rare gemstone from the taaffeite family, composed of beryllium magnesium alumina oxide (Be(Mg,Fe,Zn)_2Al₆O₁₂). It was discovered in 1967 in the Musgrave Ranges of Australia (hence the name). Musgravite typically occurs in greyish-green, olive, and violet-gray colours; on rare occasions, it can be a saturated medium purple or green. It is transparent to translucent with a hardness of 8–8.5 and has a brilliance similar to spinel or sapphire when well cut. Because it forms in extremely limited geochemical environments, facetable musgravite is virtually never encountered. In fact, for decades after its discovery, only a handful of tiny crystals were identified. Visually, it can resemble taaffeite or certain spinels, but its composition and spectroscopic properties are distinct. Collectors covet musgravite not for its fiery colour but for its scientific rarity – owning one is like owning a piece of the periodic table that almost never crystallizes as a gem.
Value (Price per Carat): Given so few musgravites have ever been faceted, their price per carat is extremely high, often cited as around $35,000 per carat for gem-quality material. Some smaller stones (under 1 ct) have sold in the five-figure range. A 2 to 3-carat musgravite of fine quality could easily be valued in the mid-six figures. The price is somewhat notional due to limited transactions – for example, if an investor paid $100k for a 2.0 ct stone, that sets a ~$50k/ct benchmark, but there may not be another trade for years. Musgravite’s value rivals red beryl and jeremejevite among collector gems, but surpasses them due to even greater rarity. It’s notable that when musgravite was first confirmed as a new gem species, it was hailed as possibly the rarest gemstone on Earth (surpassing even painite at that time). To this day, fewer than 50 faceted musgravites are believed to exist, so each commands whatever premium an eager collector is willing to pay. In summary, prices above $30k/ct are common for musgravite, and truly fine larger pieces can approach or exceed $50k+ per carat in the niche collector market.
Primary Sources: Musgravite was originally found in the Musgrave Range of South Australia, but that source produced only microscopic grains initially. Since then, a few other localities have yielded small quantities: Greenland (in manganese-rich skarns), Madagascar, Tanzania, and even Antarctica (tiny crystals found during research). The most significant source for gem musgravite to date has been Mogok, Myanmar, where a couple of gemstones identified as musgravite were found in the 1990s. Additionally, the Tunduru alluvial deposits in Tanzania produced some stones initially misidentified as taaffeite, later confirmed as musgravite. Overall, no deposit has produced musgravite in any consistent amount – we’re talking about a few crystals here and there. By 2005, only eight gem-quality musgravite stones had been documented worldwide. Even today, each new discovery of musgravite (often as a byproduct of mining for sapphires or spinel in places like Mogok or Tunduru) is a significant event in the gem community. It remains one of the least available gemstones on Earth in spite of its presence in a few scattered locales.
Acquisition: Collectors of rare gems are virtually the only buyers of musgravite – it’s not a stone you’ll find in any jewellery store. When a musgravite comes on the market, it often trades privately among a small network of rare stone dealers and collectors. Some musgravites have been offered through online speciality auctions or by dealers at gem shows (like Tucson), with prices reflecting their museum-level rarity. Ultra-wealthy gemstone connoisseurs often assemble collections of “the rarest of the rare,” and musgravite is a trophy in that realm. High-end auction houses have occasionally included musgravite in curated gemstone sales, but it’s uncommon due to the tiny supply. For example, in 2020 a 3+ carat musgravite appeared in a Christie’s online sale of rare gems and attracted competitive bids from collectors. Generally, to acquire musgravite, a billionaire enthusiast would work with a specialized gem broker or dealer in collectibles. Dealers in Sri Lanka or Thailand who handle alexandrite and taaffeite might have access to musgravite when one surfaces. Because of the stone’s obscurity, transactions often involve educating the buyer about its significance. In short, musgravite is a gemstone one seeks out through expert channels; it’s a true collector’s item that only the most dedicated (and well-funded) gem lovers even know to look for.

10. Black Opal

Description (Colour & Composition): Black opal is the rarest and most valuable type of opal, distinguished by a dark body tone (black or dark gray) that dramatically accentuates its play-of-colour. Like all opal, it is composed of amorphous hydrated silica (SiO₂·nH₂O) with sub-microscopic silica spheres that cause diffraction of light into spectral colours. In black opal, the background (or potch) is dark, so the flashes of red, green, blue, and orange fire appear especially vivid and electric against it. High-quality black opal can display every colour of the rainbow in broad patterns across the stone’s face – sought-after patterns include “Harlequin” (mosaic patches of colour) and “flagstone” patterns. Black opal’s hardness ranges from 5.5–6.5, and it must be handled with care. The most famous black opals exhibit a dominance of red and multi-colour flashes on a jet black body. This combination of dark base and brilliant play-of-colour makes black opal arguably the most visually stunning opal variety.
Value (Price per Carat): The finest black opals can reach prices around $10,000 per carat or more, rivaling some diamonds and rubies. For instance, an exceptional 306 ct Lightning Ridge black opal known as “The Royal One” was valued at about $3 million (over $9,800/ct). Even smaller high-grade black opals (5–10 ct) often sell for tens of thousands per carat. Typical good-quality stones in the 1–2 ct range might fetch $1,000–$5,000/ct depending on brilliance. An extremely bright red-on-black opal could exceed those ranges. One extraordinary piece, the 63.3 ct “Virgin Rainbow” opal (a black crystal opal), has been valued in the seven figures (though it’s not for sale). Black opal’s value is assessed by the intensity and distribution of its play-of-colour, with red being the rarest and most valued colour flash. Because these opals are unique, prices can vary widely, but truly top specimens firmly occupy the realm of gems only millionaires can afford.
Primary Sources: Lightning Ridge, New South Wales, Australia is synonymous with black opal. It is the primary (and historically, virtually the only) source of true black opals since their discovery there in the early 1900s. The Lightning Ridge opal fields produce nodules (“nobbies”) of opal in a dark claystone; from these come 95%+ of the world’s black opals. A few black opals have also been mined at Mintabie (South Australia) and more recently, some dark-based opal comes from Shewa, Ethiopia (though Ethiopian opal has different properties and often a greybody rather than true black). Another Australian locality, Andamooka, produces “black matrix opal” that is treated to enhance colour. Essentially, if one seeks natural untreated black opal, Lightning Ridge is the source. The opal fields there – such as the famous Twelve Mile and Coocoran fields – have yielded legendary stones (e.g., the “Aurora Australis” opal, 180 ct). Black opal is geologically rare because very specific conditions of silica deposition and iron oxide presence create that dark base; Lightning Ridge uniquely had that recipe in abundance.
Acquisition: High-end jewellery collectors and opal enthusiasts acquire black opals through a few channels. Many top black opals are sold at speciality opal dealers and auctions in Australia; for example, the annual Lightning Ridge Opal Festival often sees private sales of significant stones. Internationally, major auction houses occasionally feature black opals in their jewellery sales (usually set in pieces by Cartier or Louis Vuitton). For instance, Bonhams Australia has held opal-focused auctions given local demand. Ultra-wealthy buyers also source black opals via renowned dealers like Black Opal Direct or Opal Auctions, which cater to serious collectors worldwide. Some elite jewellers incorporate black opals into statement pieces – e.g., Cartier’s high jewellery opal necklaces – and those pieces are sold to VIP clients. A few famous black opals have ended up in museums: the South Australian Museum displays the Virgin Rainbow and Aurora Australis opals, reflecting their cultural value. However, most transactions are private. Wealthy collectors often have relationships with opal miners or intermediaries at Lightning Ridge who notify them when a remarkable gem is found. In summary, while not as publicized as diamond sales, the trade in top black opals is an exclusive arena, with billionaire collectors and luxury houses quietly competing for the most fiery and beautiful specimens from Lightning Ridge.