Rapaport Magazine
Style & Design

Coveted Corundum


With sources ranging from Kashmir to Montana and with colors spanning the rainbow spectrum, sapphires are among the most sought-after stones on the market.

By Diana Jarrett


The world’s love affair with sapphire stretches back through history. The precious blue gem enjoyed high status in ancient Greece and Rome, and primeval royalty believed it safeguarded owners from envy and harm. Poets have rhapsodized over it: “A purer sapphire melts into the sea,” wrote Alfred Lord Tennyson in the 19th century. And the allure has never waned.

Of course, when professionals say “sapphire,” they mean the blue variety, but “fancy sapphire” comprises a dizzying rainbow of other tints.

Where to find them

Fortunately for collectors, there are sapphire deposits on many continents. If you were to dot a global map with each place the corundum variety appears, you’d find dots almost everywhere, including the United States.

Legendary cornflower-hued Kashmir sapphires set an almost unattainable standard for this gem. Their velvety quality derives from minute inclusions that pepper the crystals like dust in a shaft of sunlight, diffracting and reflecting light. This softens the entire effect of the stone, imparting a distinctive “sleepy” glow.

The relatively brief period of Kashmir sapphire’s harvest occurred in the late 19th century; since that short run, production has been sporadic, keeping Kashmir sapphire a prize to covet.

Kashmiris may occasionally bring out old-stock crystals previously secreted by their elders, says gemologist Eddie Cleveland of Bangkok, Thailand, who is an expert in this sapphire variety. A local tribesman once showed Cleveland some long-forgotten specimens buried inside the walls of his house, which he’d only discovered when breaking through to enlarge the dwelling. “Another friend recently found Kashmir crystals in the Chenab riverbed, downstream from the original mine site,” Cleveland relates. That’s a rare occurrence, but stones can pop up in summer when the glaciers have melted further up the Himalayas.

In modern times, sapphires have been sourced in Myanmar (Burma) and Sri Lanka. Australia also produces commercial quantities of the material, as do Thailand, Cambodia and Madagascar.

More recently, Montana sapphires — in fancy-color, bi-color and parti-color varieties — are gaining traction with US consumers who favor home-grown goods and unusual hues.

“Montana sapphire has been steadily gaining in popularity,” says gemstone cutter John Dyer. “While some jewelers are prejudiced against it [because] many don’t have quite as vivid a color as a Sri Lankan sapphire, the end consumer often isn’t looking for or expecting the kind of ‘candy’ colors that jewelers have been taught is the color to buy.”

One jeweler who works regularly with Montana sapphire is Robin Callahan, a designer and lapidary artist in Bainbridge Island, Washington. “We do mine runs in Montana, so I always have hundreds to choose from at any given time,” she says. “My clients love that they are mined and cut in the US. I’ll source sapphires from other locations, but most customers are thrilled that I do the mine runs, sort through the gravel, and then send them to my favorite gem cutters. I will even cut some as well.”

Her clients also appreciate that Montana stones “may produce color shifts under different lighting. ‘Dreamy’ is often used to describe their hues. And teal is a much-requested color.” While a stone’s source may be central for certain collectors, that’s not always the case. “The average customer doesn’t know much [about sapphires’ origins], so I educate them,” says Callahan.

Taking the heat

Rough corundum isn’t always pretty, and it’s common to remedy its unattractive characteristics through heat treatment. Sapphire has been heat-treated for millennia to create desirable blues, dissolve needle-like rutile inclusions, remove color zoning and improve clarity.

Originally, the gems were packed into ground-stone pastes or clay, then deposited into a fire where blowpipes or a bellows would raise the temperature by increasing the oxygen flow. While these temperatures never reached the heat level that modern equipment can create, they did produce more salient stones. In the last few decades, sapphires have been subjected to temperatures as high as 1,700 degrees Celsius. At these levels, fine rutile needles and silk inclusions dissolve, and there is a clear improvement in color and clarity. This treatment also turns colorless sapphires into lively blue ones, while lower temperatures can lighten darker stones. In addition, heating to between 1,200 and 1,600 degrees Celsius can improve on or create asterism — the light pattern that characterizes a star sapphire — though such stones are less popular today.

Most commercial-grade sapphires these days have been thermally enhanced, so dealers make the declaration “Assume heat” whenever they don’t know for sure. Stones may go through heating more than once before reaching the desired colors.

To a lab professional, there are various indicators of heat treatment. Under a microscope, dendritic (tree branch-like) inclusions may be one sign of a sapphire’s thermal enhancement. Other signs might include cloudy particles, fingerprint-like fluid inclusions, or a more even color throughout the crystal (reduced color zoning). All of this means it’s a big deal when sapphires are verified as “no heat.”

While many consumers aren’t savvy about sapphire treatment, information is slowly reaching the public. Callahan recognizes that shift among her clients now, noting that “a growing number do know about gemstone treatments and ask if they are heated.”

Heat treatment is permanent in sapphire, but other processes may not be. Beryllium diffusion came on the scene a few decades back, usually as a last-ditch effort for poor-quality stones that failed to improve under heat. And fracture filling can enhance appearances, though it is rare in sapphires now and isn’t a long-term fix.

Disclosure is key, of course, given that sapphires with such treatments have generally sold at lower price points. When these methods first appeared in the late 1990s, the treated stones often went undisclosed on the market. At the time, it was difficult to identify fracture filling or beryllium diffusion, but today, testing procedures can detect them.

“Asian labs [see] beryllium (Be) in a very small percentage of heated stones, so [it’s] not common to the extent that it was 10 years ago,” explains Cleveland.

For Montana sapphires, with their already exotic color palette, heating may not always be warranted. “I’ve only heated a few,” says Callahan. “Most are glorious as is.”

The costs of quality

Dyer sees top-quality sapphire becoming harder to acquire as global economies rebound and with China positioned as a powerful consumer-driven market that’s scooping up quality goods.

“Often, the rough at its source is very expensive, making it hard to purchase at a good enough price to resell into the US wholesale market,” he says. “This is still possible, but we find that purchasing must be done with extra care. In the medium to long term, should market conditions hold or improve, I think we will see price increases at all levels. Demand is high, and supply hasn’t increased to match it.”

Gemstone faceter Roger Dery, founder of Roger Dery Gem Design, gathers stones directly from the source. “We are always excited about new finds. However, with Covid-19 reducing the number of miners and mining operations, there is less exploration taking place. So on the ground in these mining regions, we are not seeing much in new supplies.”

For him, quantity never outranks the importance of buying quality. “In our experience in colored gems, sapphire leads the way in interest, excitement and total dollars. We’ve just returned from Sri Lanka [in mid-July]. We found prices up noticeably from our previous visit the year before.”

Still, Dery insists “they’re a good investment. Quality sapphires will sell. But the retailer needs to have them readily available to move them.”

When it comes to US-produced goods, buyers can still grab a good thing at attractive prices. In addition to traditional blues, Montana sapphires come in grey, green, blue-green, yellow, yellow-green, and orange, says Dyer, as well as bi-color and parti-color patterns.

“They appeal to many clients today and are still relatively affordable when compared to sapphire from overseas sources, even when comparing a gem of a similar color,” he says.

Dyer admits that he finds their relatively low prices puzzling. “You would expect a US origin to command more of a premium in the market than it does so far. I believe they are still a very good value.”

As for Kashmir sapphires, their rarity means the few that make it to sale are thrilling for connoisseurs. The Sotheby’s Geneva Magnificent Jewels and Noble Jewels auction in May, for instance, included a stunning two-stone sapphire brooch with diamonds. The 1930s estate piece, which belonged to Maureen Constance Guinness, marchioness of Dufferin and Ava, boasted a presale estimate of CHF 1.9 million to CHF 2.8 million ($2.1 million to $3.1 million). When the hammer came down on the winning bid, the jewel brought in CHF 3.5 million, or $3.8 million. The heroes of this ribbon-shaped brooch were the two Kashmir sapphires: an oval stone of 55.19 carats and a cushion-cut stone weighing 25.97 carats. Kashmir specimens over 30 carats are exceedingly rare, so these extraordinary unheated sapphires were the spectacle of a lifetime for those fortunate enough catch a glimpse prior to the sale.

“Due to the cost of rough, one of the biggest challenges is creating a beautiful sapphire gem without losing too much weight,” explains Dyer. “Choosing to cut a pear shape, an oval or a round can make quite a difference in its finished weight. The same can be said about making the right choice of where to place the table facet relative to the original rough.”

Finding good prices plus quality is an ongoing quest. But so is ethical sourcing. Dery says trimming his cache of working suppliers has allowed him to dive deeper into ensuring greater transparency in his individual supply chain. “This creates a deeper level of accountability with our suppliers,” he asserts. “We are looking five to 10 years out as to what we want the relationships and the buying scenarios to be, giving greater scrutiny in each region when we can.”

As long as sapphires maintain their luster in the eyes of collectors, there will be a call for quality specimens, irrespective of escalating prices.

Article from the Rapaport Magazine - September 2021. To subscribe click here.

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