Distinguishing Features
Sapphire is the September birthstone and the gem commemorating the 5th and 45th wedding anniversaries.
Kashmir Blue describes intensely saturated and velvety, rare sapphires from Kashmir that set the standard for blue.
Sapphire has excellent toughness, stability and no cleavage, making it great for rings and other mountings subject to daily wear.
The Most Desirable Picks
Colour:
Blue sapphire ranges from very light to very dark greenish blue to violetish blue. The most valued blue sapphires are velvety blue to violetish blue, in medium to medium-dark tones, with strong to vivid colour saturation.
Clarity:
Sapphires with extremely high clarity are rare and very valuable. They are usually expected to have some inclusions, although they normally have better clarity than rubies. Price can drop if the inclusions threaten the stone's durability.
Blue sapphire is unique because inclusion may increase the value of some sapphire. Tiny inclusions give a velvety appearance to the most valuable Kashmir sapphires. They scatter light without negative effects on the gem's transparency.
Cut:
Cutters evaluate factors like colour zoning, pleochroism, and the lightness or darkness of a stone, to achieve the best overall colour, maintain the best proportions, and retain the most weight possible.
For phenomenon sapphire such as star corundum, a cabochon is usually the shape. A finished stone's attractiveness increases if the star is centred correctly, the stone's outline is symmetrical with an appealing proportion and finish.
Carat weight:
Sapphires can range in size anywhere from a few points to hundreds of carats; the price per carat increases more dramatically with larger stones and higher quality. Large blue sapphires are more readily available than large rubies. However, most commercial-quality blue sapphires are less than 5.99 carats in weight.
Origins
Origins in trade:
Just like rubies and emeralds, a few trade terms are used to describe the qualities associated with certain geographical sources. While sapphires may exhibit special characteristics representative of their source of origin, origin does not always guarantee quality. Traders and consumers should also avoid speculating on a gem's source based on its appearance. A certificate from a prestigious independent gemological laboratory is a strong reference to identify the source. Nevertheless, it would be helpful to understand the general indicating qualities of the gems when they are associated with certain sources. Bear in mind that appearances can be deceiving. A mine can produce gems of various qualities and judgement can be quite subjective.
"Kashmir" describes sapphires with violetish blue to pure blue hues, with moderately strong to vivid saturation and medium-dark tone, setting the standard for the finest quality blue sapphires. Minute inclusions can give a velvety appearance and desirable softness while intensifying their colour, which is often referred to as "cornflower blue".
"Burmese" describe sapphires with a slightly violetish blue to blue hues, with moderately strong to vivid saturation and medium-dark tone. Their colour can be more intense and saturated than Kashmir sapphires, somewhat inky under incandescent light, but lacks a velvety appearance. Sources such as Madagascar can produce stones of very similar quality and visual appearance.
"Ceylon" and "Sri Lankan" describe sapphires that have a violetish blue to blue hue, with slightly grayish to strong saturation and light to medium-light tone.
"Australian" indicates a dark, inky colour that sometimes appears silky or cloudy. "Pailin" stones are considered to have better quality blue colour, might also have a velvety appearance.
"Royal Blue" describes a deep, highly saturated blue.
Global Sources:
Kashmir, Myanmar (formerly Burma) and Sri Lanka are three historically important sources. At the same time, several newer sources around the globe produce high-quality sapphires that can rival the old mines.
Kashmir:
Sapphires were discovered in Kashmir around 1881 when a landslide high in the Himalayas exposed a large pocket of velvety "cornflower" blue crystals. From 1882 to 1887, thousands of large, beautiful crystals were recovered. The stones faceted from these crystals established Kashmir sapphire's reputation as one of the world's most coveted gems. Production has been sporadic since then, but auction houses occasionally sell fine pieces of Kashmir sapphire jewellery.
Myanmar (formerly Burma):
"Burmese" sapphire can possess a rich, intense blue hue. They can command some of the highest prices on the market. Sapphire typically occurs alongside ruby deposits in Myanmar but in much smaller quantities.
Sri Lanka:
Sri Lanka produces what some consider the broadest range of sapphire colours globally. It has been a premier source of corundum for centuries. It is regarded as the most important source of star rubies and sapphires. Known as an "island of gems", most gemstones are recovered from alluvial deposits in riverbeds, streams, and rice paddies. Most fine sapphires over 100 carats are from Sri Lanka.
Thailand:
Thailand is both a source of sapphire and a major cutting and treatment centre.
Sapphires have also been found in Australia, Cambodia, Madagascar and the United States (Montana), among other countries in Asia and Africa.
Madagascar:
In the 1990s, the island emerged as a significant source of good to fine quality blue sapphire.
Nigeria:
Nigeria became a significant source of blue sapphire since 2014. The stone was large and clean, some weighing between 100 and 300 carats.
Cambodia:
The Pailin corundom deposit has a long history of supplying fine-quality blue sapphire as well as commercial qualities in small sizes. However, the production is unpredictable due to the restrictions on mining.
Australia:
Australia is one of the world's major sources of dark blue, commercial quality sapphire. The bulk of the supply is dark, inky blue, with a strong greenish tint due to pleochroism and colour zoning. The country also produces some high quality, nicely colour stones.
Montana (US):
Yogo Gulch in Montana is famous for small, fine colour blue sapphires without heat treatment. Sometimes, two times heating is applied to turn some corundum blue.
Other Sources:
China, Vietnam, Laos, Tasmania, and Cameroon are other sources of corundum around the world.
Significant Pieces
Princess Diana's sapphire blue engagement ring may be one of the most recognizable pieces of jewelry in history. The white gold ring, called the Marguerite, featured a 12-carat oval Ceylon sapphire that was surrounded by 14 solitaire diamonds. The centre stone holds a desiring colour of "Royal Blue".
Today, the ring is as visible as ever, worn by the Duchess of Cambridge as her own engagement ring. Prince William chose to propose with the ring. "I thought it was quite nice because obviously she's not going to be around to share any of the fun and excitement," said Prince William of Diana at the time of his engagement to Kate Middleton in 2011. "This was my way of keeping her close to it all." After decades of speculation, we are perhaps as close as we'll ever be to understanding how the famous ring came to be owned by the People's Princess.
Today, the ring is as visible as ever, worn by the Duchess of Cambridge as her own engagement ring. Prince William chose to propose with the ring. "I thought it was quite nice because obviously she's not going to be around to share any of the fun and excitement," said Prince William of Diana at the time of his engagement to Kate Middleton in 2011. "This was my way of keeping her close to it all." After decades of speculation, we are perhaps as close as we'll ever be to understanding how the famous ring came to be owned by the People's Princess.
Formation
The mineral corundum is composed only of aluminium and oxygen, and it requires a growth environment that's free of silicon. However, silicon is a common element, making natural corundum relatively uncommon. The trace elements iron and titanium cause the blue of sapphire, making natural blue sapphire even rarer; only a few parts per million atomic can have the colour.