Sapphire: The Many Colors of Corundum

Sri Lanka is one of the oldest continuously worked sapphire sources in the world, and one of the most varied. The gem gravels around Ratnapura have been worked for at least two thousand years. Most production comes from secondary gravels in the Ratnapura, Elahera, Balangoda and Rakwana districts, eroded largely from high-grade metamorphic rocks. Sri Lankan material spans blue, pink, yellow, orange, violet, colorless, star and padparadscha sapphires. Many of these stones are relatively low in iron, which helps keep their colors bright and, when chromium is present, allows them to fluoresce red.

The legendary Kashmir deposit lies near Sumjam in the Paddar region of the northwestern Himalaya. Around 1881 a landslide exposed sapphire-bearing rock, and the richest workings, known as the "Old Mine," were exploited most intensively between 1882 and 1887. Later exploration and intermittent mining produced far less. The sapphires occur at high elevation, in metasomatically altered rocks associated with pegmatitic intrusions. The finest Kashmir stones are prized for a saturated blue combined with tiny light-scattering particle clouds, which together create their famous velvety look. Fine historic Kashmir material is exceptionally scarce, but a Kashmir origin alone does not guarantee that a stone shows the classic appearance.

For more detailed information on this legendary deposit, its geology, history and the look of its stones, read our article Kashmir Sapphires: The Legend of the Blue Treasure.

Myanmar's best-known sapphires come from the Mogok Stone Tract, where gems were mined long before any European record and which came under direct Burmese royal control in 1597. The sapphires occur in both metamorphic and alluvial settings, within the same complex terrain that produces ruby, spinel and many other gems. The finest unheated stones can show a rich, strongly saturated blue. Pinning down a Burmese origin can be difficult, because some inclusion and chemical features overlap with those of other metamorphic deposits.

Madagascar became a major modern supplier after 1998, when extensive alluvial deposits were discovered around Ilakaka and Sakaraha. These placers, derived from metamorphic rocks, yield blue and fancy-color sapphire across a wide range of qualities. Other important areas include Andranondambo in the south, Didy and Bemainty in the northeast, and several smaller fields. The Bemainty rush began in 2016 and produced fine blue material. Madagascar supplies everything from commercial rough to exceptional stones comparable in appearance to those from the classic Kashmir sources. Some sapphire rushes have spread into protected forest areas, which makes environmental impact and supply-chain documentation part of the picture alongside gem quality.

Tanzania has several geologically distinct sapphire districts. The Umba Valley deposit, discovered in 1962, is known for its wide range of colors and strong zoning. In the south, Songea was discovered in 1992 and was productive until 1994, when fine blue, yellow and pink sapphires were found near Tunduru. Songea became commercially important again in the early 2000s, when beryllium diffusion turned its muddy green and brownish purple stones into attractive yellow to orange sapphire. Winza, found in 2008, is better known for ruby but also yields sapphire.

Kenya's Dusi deposit near Garba Tula, found in 2004, produces blue, green and yellow sapphires from a corundum-bearing dike. It is a primary magmatic deposit, meaning the sapphire crystallized right there in its host rock, and it remains one of very few documented occurrences of gem corundum formed directly in igneous rock.

Mozambique also produces sapphire, although ruby dominates its international reputation, particularly since the Montepuez discoveries of 2009. The corundum deposits of northern Mozambique yield pink and violet sapphire as well as ruby. Malawi's Chimwadzulu deposit is another East African source, producing ruby together with pale green, blue, yellow and orange sapphire from a geologically complex metamorphic setting.

Montana has both primary and placer deposits, and gem sapphire has been mined there for more than a century and a half. Gold miners found the first crystals in 1865, in gravel bars along the upper Missouri River northeast of Helena, and the first scientific description followed in 1873. Dry Cottonwood Creek was found in 1889, and Rock Creek, today the most productive site in the state, in 1892. Yogo Gulch, Montana's main primary deposit, was discovered in 1895 when prospector Jake Hoover recovered blue pebbles from his sluice; the same year, the material reached Tiffany & Co. in New York. Yogo sapphires occur in a lamprophyre dike. They are typically small but well colored, with a fairly even blue and little need for heat treatment. Some of Montana's placer rough, by contrast, is commonly heated.

Eastern Australia has produced large quantities of basalt-related sapphire since the 19th century. Important fields include the New England district of New South Wales and the Anakie, Rubyvale and Sapphire districts of central Queensland. Much of the material is dark blue, greenish blue or parti-colored because of its relatively high iron content, although attractive lighter stones also occur. Australian rough played a major part in the growth of Thailand's cutting and heat-treatment industry.

The Chanthaburi-Trat district of Thailand and the Pailin region of Cambodia are classic basalt-related sources, both worked commercially since the 19th century. They once produced large volumes of dark blue sapphire and supported major treatment and trading centers, although many of their deposits are now far less productive. Vietnam produces sapphire from both metamorphic terrains and basalt-related placers: the Luc Yen area in the north was found in the mid-1980s, and further material comes from the central and southern parts of the country. Laos is known particularly for basalt-related sapphires near Ban Houay Xai. These Southeast Asian stones usually contain more iron, and have weaker fluorescence.

Gem sapphire has also been reported from Nigeria, Ethiopia, Cameroon, China, Russia, Nepal, Pakistan, Afghanistan and several other countries. Scientific occurrences are known even in Antarctica, although they have no commercial significance. Finding corundum somewhere does not mean there is an economic gem deposit, and many localities yield only small, opaque or fractured crystals.

Bulgaria also has documented corundum mineralization. Ruby- and sapphire-bearing marbles are found near the village of Mishevsko in the Kardzhali region of the Eastern Rhodopes, where corundum occurs along foliation planes together with rutile, micas, graphite and amphibole. A second occurrence lies near the village of Dorkovo in the Western Rhodopes. Purple sapphire from this area is exhibited at the National Museum Earth and Man in Sofia, and according to the museum, testing has shown the material to be rich in vanadium. They are not gem material, but still interesting collection specimens.

Inclusions are the tiny crystals, fluids and structures trapped inside a gem as it grows, and in sapphire they have a great deal to say. Among the most familiar are fine needles and particle clouds of rutile. When this rutile is fine and oriented, it’s called silk. Silk can soften the look of a transparent stone, and when it is dense enough and correctly oriented, it can produce a star. Other common mineral inclusions include zircon, apatite, spinel, feldspar, mica, calcite, monazite, ilmenite and hematite, although the exact mix depends on where and how the sapphire formed.

Zircon crystals may be surrounded by small tension fractures or altered halos. Heating can change these features, but their presence alone does not prove a stone has been treated. Negative crystals are cavities whose walls follow the shape of the host crystal; they may hold a fluid, or several phases together, solid, liquid and gas. Healed fissures often form delicate networks known as "fingerprints." Growth zoning and bands of minute inclusions record changing conditions as the crystal grew, while fractures that reach the surface can affect durability and give fillers a way in.

For a gemologist, inclusions are some of the best evidence available for natural origin, geological environment and treatment history. Very few, however, are unique to a single locality. Deciding where a sapphire came from takes microscopy, spectroscopy and trace-element chemistry, interpreted together. A familiar inclusion pattern can support an origin opinion, but it should never be treated as proof on its own.

The classic blue comes mainly from a process called intervalence charge transfer between Fe²⁺ and Ti⁴⁺. When light strikes neighboring iron and titanium ions, it can shift an electron from one to the other. This absorbs a broad band of light, and blue is what remains to reach the eye. Iron-related absorption also shapes the final result. High iron often darkens basalt-related material, although total iron content alone cannot predict a stone's color.

Kashmir, Sri Lanka, Myanmar and Madagascar are famous for fine metamorphic-type blue sapphires, while Australia, Thailand, Cambodia, Laos and parts of Vietnam are established sources of iron-rich, basalt-related blue material. Trade terms such as "cornflower blue" and "royal blue" describe appearance. Some laboratories apply their own criteria for them, but they are not universal grades and they say nothing about origin.

Pink sapphire owes its color to Cr³⁺ and the color ranges from a delicate blush to vivid pink. As chromium content rises, the color moves toward red, which raises an obvious question: what’s the difference between pink sapphire and ruby? There is no universal chemical threshold, so laboratories and markets can disagree about stones that sit near the line. Hue, tone and saturation are judged together. More about this subject will be discussed in a future article.

Purple and violet usually come from a blend: chromium-related pink or red combined with blue from Fe²⁺-Ti⁴⁺ charge transfer. Vanadium can also play an important role in some stones. Because the strength of these absorptions changes with crystallographic direction, purple sapphire can show pronounced pleochroism, shifting from bluish violet to reddish purple as you view it from different directions. Violet and purple sapphires are generally less common in the trade than blue ones.

Yellow sapphire may be colored by Fe³⁺-related absorption or by trapped-hole centers associated with iron. A trapped hole is a spot in the lattice where an electron is missing. Magnesium, through charge compensation, can help create these centers. Having more than one mechanism explains why some yellow colors are completely stable, while others respond to light or heat.

Orange sapphire can combine chromium-related pink with a yellow component, but that is not the only route. Trapped-hole centers associated with chromium can produce orange by themselves. Some orange colors are intensified by heat, irradiation or beryllium diffusion, so two stones that look alike can owe their color to quite different natural or treatment-related causes.

Padparadscha is one of the most narrowly defined names in the gem trade: a pink-orange to orange-pink sapphire, usually with a soft, pastel look. The name comes from a Sinhalese term associated with the lotus blossom. Laboratory definitions differ in the details, but brown or green modifiers, very dark tones and pronounced color unevenness can all rule a stone out. Sri Lanka is the traditional source, while Madagascar and Tanzania have also produced stones that qualify.

The color is a balance between chromium-related pink and yellow or orange components. Some stones lose part of their orange component after exposure to light or during storage, then regain it under ultraviolet radiation. For this reason, laboratories check color stability before assigning the padparadscha name. A slight shift can be accepted as long as the stone stays within the qualifying color range. This kind of instability also occurs in natural stones, so on its own it does not prove artificial irradiation. Stones colored by beryllium diffusion or filled with colored glass do not qualify as padparadscha. Details about this coming soon in an in-depth article.

Green sapphire usually results from blue and yellow absorption systems working together. A pure, vivid green is less common than blue-green, yellow-green or gray-green.

Parti-colored sapphire shows two or more distinct color zones in a single stone. Australia is especially associated with blue-yellow and blue-green parti sapphires, although similar material occurs elsewhere. With these stones, the way the cutter orients the rough makes a very large difference to the finished look.

Colorless sapphire contains very little active color-causing impurity, or a balance of defects that cancels out their absorption. Transparent colorless stones are commonly called white sapphire. Milky white material gets its cloudiness from particles or other internal structures that scatter light. Gray sapphire may result from weak mixed absorptions, fine inclusions or dark zoning.

Brown sapphire can involve iron-related absorption, defect centers and mixtures of several color mechanisms. Many stones sold as black sapphire are in fact very dark blue, green or brown, or are opaque because they are packed with inclusions. Black star sapphires commonly contain oriented hematite or ilmenite-related inclusions, which produce a star against an opaque, dark bodycolor.

Yellow, orange and near-colorless sapphires can show yellow-orange to reddish-orange fluorescence. Recent studies link these emissions to F-type centers associated with oxygen vacancies and their interactions with magnesium-associated trapped-hole centers. One proposed model attributes much of the orange emission to paired oxygen vacancies associated with divalent impurities, principally magnesium, with beryllium potentially playing a similar role in Be-diffused corundum. These mechanisms remain under investigation, and fluorescence intensity does not necessarily follow the strength of the sapphire’s yellow bodycolor.

Some heated low-iron sapphires show chalky blue or whitish fluorescence under shortwave UV, often distributed in patches or bands. During heating, rutile inclusions can partially or extensively dissolve, releasing titanium into the surrounding corundum lattice. This can create luminescent centers involving Ti⁴⁺ ions and associated lattice defects. Their blue emission is commonly attributed to oxygen-to-titanium charge transfer: UV light excites an electron from a neighboring oxygen ion toward titanium, and the subsequent relaxation releases energy as visible light. The glow may follow the original distribution of rutile or chemical zoning, with the strongest reaction often occurring in titanium-rich, low-iron areas.

There is no single temperature at which all sapphires develop this fluorescence. Its appearance depends on the stone’s initial chemistry and inclusions, as well as the temperature, duration and atmosphere of heating. Iron can suppress the emission, so even strongly heated sapphires may show little or no chalky fluorescence.

This reaction can therefore provide a useful clue to treatment, but it is not exclusive to heated natural stones. Richard W. Hughes and John L. Emmett also documented weak, superficial chalky green fluorescence in some untreated natural sapphires, particularly from Madagascar, where it appeared in sharply bounded patches. Flame-fusion (Verneuil) synthetic sapphires can also show similar fluorescence. Such exceptions mean that chalky fluorescence must be assessed alongside other evidence; equally, its absence does not prove that a sapphire is unheated.

Cat's-eye sapphire shows a single narrow band of light moving across the dome in place of a star. The effect appears when one dominant set of parallel inclusions reflects light from a correctly oriented cabochon. The base is cut roughly parallel to the inclusions, so their reflection can gather into a line across the dome. Natural cat's-eye sapphire is rarer in the trade than star sapphire, and the best examples show a straight, well-defined eye.

Color-change sapphire looks different under light sources with different spectral output. It is commonly blue or violet in daylight-equivalent light and purple, reddish purple or red-violet under incandescent light. Vanadium can be an important cause, with other chromophores modifying the effect. How strong the change appears depends on the absorption spectrum, the light sources and the observer's own color perception. These stones are usually faceted, and Sri Lanka and Tanzania are established sources. If you compare lights yourself, keep the viewing direction the same, because simply turning a pleochroic sapphire can also change its apparent color. A warm-white LED may not reproduce the look under a true incandescent lamp.

Colored sapphire is dichroic: it can show two different bodycolors or color intensities when viewed along different crystallographic directions. Its coloring centers absorb light differently depending on the orientation of the light’s vibrating electric field, known as its polarization. Because corundum is optically uniaxial, it has two principal absorption spectra, corresponding to light polarized parallel and perpendicular to its crystallographic c-axis. These produce two characteristic pleochroic colors, whose relative contributions change as the stone is turned. Blue sapphire may show blue and greenish blue, while purple material can show violet and reddish purple.

Pleochroism is an intrinsic property of the crystal, so it can occur even in sapphire with completely uniform chemical composition. It strongly influences cutting orientation: cutters assess these directional colors to obtain an attractive face-up appearance, while also considering color zoning, inclusions and the light paths created by the facets.

Some inclusion-rich sapphires show a metallic golden or silvery sheen from reflective platelets lying in parallel. Kenyan material marketed as golden sheen sapphire owes this effect chiefly to hematite and ilmenite inclusions and is commonly cut as cabochons. This sheen, whether fixed or shifting, is different from a sharp star, although both can appear in the same stone.

Simple heating of corundum has a long history in South and Southeast Asian gem traditions, but exact early dates and temperatures are poorly documented. Modern controlled heating expanded rapidly during the 20th century, especially once Thailand began heating milky Sri Lankan geuda material from the 1970s onward. Geuda is a trade category of corundum whose cloudiness and inclusions can respond to heat.

Treaters use controlled furnaces, adjusting temperature, atmosphere and heating time to suit the rough. Some color changes happen below about 1,000 °C, while stronger changes may require roughly 1,600-1,900 °C. Heating can dissolve rutile silk, improve transparency and shift the balance of color-producing ions and defects. It can deepen or lighten blue, reduce unwanted color components, or improve yellow, pink and orange. Fracture healing with the help of flux works differently and has its own section below.

Under normal wear, the results of conventional high-temperature heating are usually stable, but the popular claim that "heat treatment is permanent" is too broad to hold in every case. Some yellow and orange defect-center colors can change with light or further heating, and later high-temperature repair work can alter a stone.

Signs of heating include partially dissolved silk, altered crystal inclusions, disc-shaped (discoid) fractures, heat-related halos and changes in infrared spectra. No single microscopic feature is conclusive in every stone. Low-temperature heating can leave only subtle evidence, and a report stating "no indications of heating" describes what the examination found. It is not a complete reconstruction of everything that has happened to the stone.

Titanium diffusion was developed commercially during the 1970s and 1980s. Pale corundum is heated to a very high temperature in contact with a titanium-bearing source. Titanium works its way into the lattice near the surface and interacts with iron there to create blue. Because the treated layer can be thin, repolishing or recutting may remove some or all of it. Color concentrated along facet junctions is a telltale sign, and immersing the stone in a liquid, which cuts down distracting surface reflections, makes it easier to see. The color is generally stable in normal wear, but the stone must be disclosed as diffusion-treated.

Beryllium-diffused corundum appeared on the market around 2001, and formal trade alerts followed in early 2002. The treatment commonly takes place above 1,800 °C. Under commercial treatment conditions, beryllium can diffuse much deeper than titanium and may affect most or all of a small stone. The reason lies in the size of the ion. Be²⁺ is one of the smallest cations, roughly half the radius of Al³⁺ or Ti⁴⁺, so it can travel through the lattice interstitially and then substitute for Al³⁺. Be²⁺ changes the crystal's charge balance and can create trapped-hole color centers. It modifies yellow and orange components, producing yellow, orange, pink-orange and other colors, and it can also lighten some blue sapphires.

Routine microscopy can reveal signs of heating, but it may not prove beryllium diffusion. For that, laboratories turn to trace-element methods such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) or secondary ion mass spectrometry (SIMS), which sample only minute amounts of material. Ordinary X-ray fluorescence analysis cannot adequately test for beryllium. Even then, results have to be interpreted in context, because detecting a trace of beryllium is not, by itself, enough evidence of treatment. The induced color is generally stable in normal wear, but diffusion usually lowers value compared with otherwise similar untreated or conventionally heated sapphire, and it requires explicit disclosure.

Glass filling improves the apparent clarity of heavily fractured corundum by introducing glass into open fissures and cavities. In sapphire, cobalt-colored lead glass is especially relevant: it can add a strong blue color while also masking fractures in pale, low-quality material. Examples were reported in 2007, with further generations described in 2013. Gas bubbles, glass-filled cavities, color concentrated in fractures and colored flashes as the stone is tilted can all reveal the treatment.

The glass is softer and chemically less durable than sapphire, and it can be damaged by acids, heat, ultrasonic cleaning and jewelry repair. Material with a substantial glass content may be described as a composite of corundum and glass. The filling, its effect on color and any special care it needs should all be disclosed. Such stones are worth substantially less than a comparable sapphire without substantial filling.

High-temperature treatment with borax or other fluxes can partially heal fractures: corundum dissolves and is redeposited along the fissures. Commercially, this process is more closely associated with ruby, but it can also occur in sapphire. Residual flux, glassy films or healed channels may remain.

Irradiation can create or intensify yellow, orange and brown color centers in pale corundum. Gamma radiation is the usual method, because sources are cheap and widely available. Kurt Nassau's published work through the 1970s and 1980s established how the process works and how the color fades, and Nassau and Valente's 1987 study is still the standard reference on unstable yellow and orange sapphire. Irradiation is rarely used, because the color is usually unstable.

Coatings and dyes are less common than heating or lattice diffusion in transparent sapphire. A coating can change the apparent color but is vulnerable to abrasion and to heat during repairs. Dye can collect in open fractures in low-grade material. Uneven surface color, or color concentrated in fissures, may raise suspicion, although laboratory examination may be needed to confirm it. Both treatments should be disclosed specifically, with care advice to match.

In 1902, Auguste Verneuil announced flame fusion, the first commercially successful gem synthesis, starting with ruby. Blue sapphire followed in 1909, when Verneuil established that iron and titanium together were needed to reproduce the natural color; two patents covering it were granted in 1911. Popov refined the process in the Soviet Union during the 1930s, and Linde Air Products scaled up production in the United States during the Second World War.

Fine alumina powder and coloring oxides fall through an oxyhydrogen flame at roughly 2,000 °C, melt, and solidify layer by layer on a rotating support. In just a few hours this builds a boule, an elongated synthetic crystal. No crucible touches the melt, which is what makes the process fast and inexpensive, and it still supplies most of the synthetic corundum used in jewelry. Curved growth striae, curved color banding and gas bubbles are characteristic when present, although they may be faint or missing in the finished stone. Blue flame-fusion boules often carry intense color in thin outer zones over a much paler core, so the color of a cut stone can be uneven.

Flux growth dissolves aluminum oxide and colorants in a molten solvent, typically a lead or bismuth oxide melt, at 900-1,300 °C, temperatures well below corundum's melting point. Crystals form and grow slowly over weeks or months. The process is far more expensive than flame fusion, but it produces growth features much closer to those of natural corundum, and that is exactly what makes the material challenging to identify. Carroll Chatham established the best-known production: commercial Chatham synthetic blue sapphire was documented in the gemological literature by 1977, and a fuller study of Chatham blue and orange sapphire was published in 1982. Other flux producers, working mainly in ruby, have included Kashan, Knischka, Ramaura and Douros.

Typical features include flux veils, metallic platelets picked up from the crucible, angular growth zoning and trapped remnants of the solvent. Some flux veils resemble natural healed fractures so closely that telling them apart takes experience. Flux-grown blue sapphire often shows alternating blue and colorless angular zones that follow the crystal shape, which limits the yield of evenly colored faceted stones.

In the Czochralski process, a seed crystal is dipped into molten aluminum oxide, then rotated and slowly withdrawn, so that a large cylindrical crystal grows from it. Union Carbide, successor to Linde, developed Czochralski growth of sapphire for laser materials during the 1960s, and Czochralski-pulled, titanium-bearing pink sapphire from that source was described in the gemological literature in 1995.

Several other melt methods were developed for industry, not for jewelry. Spyro Kyropoulos described his method in 1926: the crystal grows beneath the surface of the melt inside the crucible as the temperature is slowly lowered, which avoids much of the strain and cracking that affect pulled crystals. The heat-exchanger method, invented by Fred Schmid and Dennis Viechnicki in 1967, draws heat out through a helium-cooled exchanger beneath a crucible held at a uniform temperature, and yields very large, low-stress boules. Edge-defined film-fed growth, developed by Harold LaBelle in the same period and reported in 1971, draws melt up through a shaped die by capillary action, so the crystal grows directly as a tube, rod or ribbon. Both were commercialized during the 1970s.

These techniques supply the sapphire in watch crystals, optical windows and semiconductor substrates, and the same material is sometimes faceted for jewelry. Growth structures and trace-element chemistry can help identify it. Very high clarity alone, however, is not evidence of laboratory growth.

Hydrothermal growth uses a hot, pressurized water-based solution inside a sealed vessel called an autoclave. Dissolved alumina travels from a hotter zone, where the nutrient material dissolves, to a cooler seed crystal, where it grows. Laudise and Ballman produced the first hydrothermal colorless synthetic sapphire in 1958, and Kuznetsov and Shternberg extended a modified technique to ruby in 1967. Russian hydrothermal synthetic ruby reached the international market in 1993, and Tairus of Novosibirsk introduced hydrothermal synthetic sapphire colored by nickel and chromium, described in the literature in 1997.

The commercial attraction was even color, since both flame-fusion and flux-grown blue sapphire suffer from uneven color distribution. Even so, hydrothermal material remains far less significant in the jewelry market than flame-fusion sapphire. Its angular growth features, subsurface growth structures and fluid inclusions can make it tricky to separate from natural sapphire.

Linde developed synthetic star sapphire in 1947 and began selling it in the late 1940s. Extra titanium is dissolved into a flame-fusion boule during growth, then precipitated as oriented rutile needles by a controlled anneal below the melting point. The resulting star is usually sharper, more complete and more perfectly centered than a natural one, and that perfection is itself a warning sign. Synthetic color-change sapphire, generally colored by vanadium, has been sold as an alexandrite imitation since the early 20th century.

Identification combines microscopy, UV-visible and infrared spectroscopy, fluorescence behavior and trace-element analysis. Refractive index and specific gravity confirm that a stone is corundum, but they cannot tell natural from synthetic. A neat star, strong fluorescence or a lack of visible inclusions is not conclusive on its own.

One of the most widely recognized sapphire jewels today is the engagement ring first worn by Diana, Princess of Wales, and later given to Catherine, Princess of Wales. It holds an oval blue sapphire surrounded by 14 diamonds, set in white gold. The ring was made by Garrard and chosen from an existing design. The center stone is commonly reported to be about 12 ct and Sri Lankan, although no detailed laboratory documentation has been made public.

The Stuart Sapphire, a blue sapphire of approximately 104 ct, is mounted in the Imperial State Crown. Its early history is partly traditional, and the stone has been drilled, consistent with its having once been worn as a pendant. As part of the Crown Jewels, its importance is historical and ceremonial, and any speculative market price would be misleading.

The Logan Sapphire and the Star of India, both described among the largest stones above, are among the best-known museum sapphires. The Logan is set in a diamond brooch at the Smithsonian National Museum of Natural History, whose collection also includes the Star of Bombay, a 182 ct violet-blue star sapphire from Sri Lanka bequeathed by the actress Mary Pickford.

Cartier set this 478.68 ct unheated Sri Lankan sapphire in 1913 and in 1919 displayed it in a sautoir, a long necklace, at San Sebastián. By 1921, when King Ferdinand bought it for Queen Marie for 1,375,000 francs, it had been remounted as a pendant on a diamond and platinum necklace. Christie's offered the pendant in Geneva on 19 November 2003 as the property of a noble family where it realized CHF 1,916,000. It now belongs to Qatar Museums in Doha and was shown in the Cartier exhibition at the Victoria and Albert Museum in London in 2025.

The Blue Belle of Asia is a 392.52 ct unheated Sri Lankan sapphire set in a diamond necklace. Christie's sold it in Geneva on 11 November 2014 for approximately US$17.3 million, against an estimate of US$6.9-9.9 million, setting the auction record for any sapphire measured by the total price of the jewel. It returned to Christie's New York on 17 June 2025, estimated at US$8-12 million, and sold for approximately US$11.3 million. The lower second result is a clear reminder that an exceptional stone's previous auction price is no guarantee of its resale value.