For many people, sapphires are the most beautiful gemstones in the world, and they are extremely popular among those passionate about jewellery. Although sapphires may not be as valuable as Burmese pigeon blood rubies or fancy coloured diamonds, these blue gemstones are still extraordinarily highly regarded and sought after.
[left]Sapphire is a variety of the Corundum species that occurs in every colour except for red (red corundum is known as Ruby), although its purest form, colourless (white) gem quality corundum is exceedingly rare. It is the second hardest mineral on Earth after Diamond, rated 9 on Mohs scale (the measurement scale of mineral hardness).[/left]
Tutti Frutti Necklace by Cartier
[left][left]The word Sapphire comes from the Persian word “safir“, derived from the Greek word for blue. In antiquity, the word sapphire was used to describe a number of blue gemstones, but in the early 19th century this changed and it was assigned to the variety of corundum that we know today. Now, when the word “sapphire” is used on its own it implies a blue sapphire, with other colours being used as a prefix, such as “green” or “orange” sapphire. Coloured sapphires are often referred to as “fancy” sapphires. Most natural sapphire is somewhat pale in colour and only a very small percentage exhibits a bright, vivid colour. Consequently, the majority of these gemstones are heat-treated to enhance the colour.[/left]
How do you recognise a sapphire?
Sapphire exhibits an attractive bright vitreous lustre, and can occur in transparent to opaque forms. The most valuable ones are the transparent sapphires with an even, saturated colour throughout the gemstone.
One of the most common characteristics of a sapphire is the presence of rutile needle-like inclusions which are often called ‘silk’. In some cases, fine silk throughout the stone can enhance the value of some sapphires. The most famous sapphires from the Kashmir region in India have a velvety vivid cornflower blue which is caused by this feature. When in a regular orientation these inclusions also cause the asterism effect in star sapphires. Too much silk, however, will weaken the colour.
Other typical characteristics of sapphire are “zoning”, where the colour appears to be concentrated in parallel bands, and zircon inclusions, particularly in some of the sapphires from Kashmir, Burma and Sri Lanka. Zircon is often found with these blue gemstones in gem gravels, and, as it is mildly radioactive, it tends to destroy the crystal lattice structure of the host material, creating the distinctive “ halo” inclusion.
Where can you find sapphires?
Some of the most common places to find sapphires are Kashmir (India), Myanmar (Burma), Thailand (Siam), Sri Lanka (Ceylon), Pailin (Cambodia), USA (Montana), Australia and, since 1998, Ilakaka (Madagascar). Blue is the best known and most prized of the sapphire colours, and of these the most highly demanded are the ones from Kashmir, Sri Lanka and Burma, which traditionally have a deep, intense and velvety blue. Unfortunately, since 1920, there haven’t been any significant discoveries in these mines, and Sri Lankan and Madagascan sapphires are the most common on today’s market and range from light to dark blue.
Sri Lankan sapphires are considered to be among the best in the world. A range of coloured sapphires can be found here, including the rare pinky-orange Padparadscha, and approximately 90 % of the world’s star sapphires also come from this island. Mining methods are relatively primitive, and when gravel is extracted from current riverbeds it is done with hand-made scrapers. Thailand is another major sapphire source; these sapphires tend to be very dark in colour and often resemble a blue spinel. Thailand has become the primary processing and trading centre for most coloured stones, including sapphires.
The darkest coloured sapphires tend to be Australian, and they are consequently the least valuables. Heat treatment is nearly always used for the Australian sapphires to lighten the colour.
A particularly rare, fine, deep blue and distinctively pure sapphire is found in Pailin, Cambodia, and it is well known amongst gem traders for its superior quality. Finally, in the 19th century, a pale electric-blue sapphire was discovered in Montana (USA) and used in jewellery before First World War.
How do you cut a rough crystal of sapphire?
Sapphires are cut in different shapes, with the round and oval cut being the most common. However, you can also find fancy shapes such as heart, pear, and emerald cuts. Cabochons are the standard cut for included, translucent to opaque stones or for star sapphires.
What treatments can be applied to sapphires?
Nowadays most sapphires are heat treated for a few hours to temperatures of around 1700-1800° Celsius to improve their clarity and colour before being cut. Natural, unheated stones are extremely rare and will command enormous prices. Star sapphires can also be diffusion treated to improve the quality of the star and, for coloured sapphires; beryllium treatment can be used to produce beautiful orange and red colours. All these treatments have to be fully disclosed before purchase.
How many types of sapphires can you find?
Blue sapphire: the best blue colours are the rare and fine “Kashmir Blue” from India, and the Cornflower Blue described as an intense, velvety-blue.
Fancy sapphires: any corundum that is not red or blue; these can come in any other colour of the spectrum. Padparadscha is an extremely rare sapphire, with an intense orange-pink that is found in Sri Lanka.
Colour change sapphire: sapphire that exhibits a different colour depending on whether it is viewed in natural or artificial light.
[left]Star Sapphire: a form of sapphire that displays asterism (a six-rayed star) due to the presence of regularly orientated needle-like inclusions[/left]
Star of Asia :329-carat sapphire
* With a weight of 536 carats, the Star of India is the largest star sapphire in the world. Discovered in Sri Lanka, this beautiful sapphire was donated by the financier J.P Morgan to the American Museum of Natural History.
* The Rockefeller sapphire, purchased in 1934 by John D. Rockefeller from an Indian maharajah, is a blue rectangular step-cut sapphire of 62.02 carats currently mounted in a diamond ring. In 2011, Christies sold it for $3,031,000.
[left]* The Logan Sapphire is the largest blue faceted sapphire in history, at present displayed in the Smithsonian Museum of Natural History. The 423 carat cushion-cut stone from Sri Lanka is set in a brooch surrounded by 16 carats worth of diamonds[/left]
[left]* The engagement ring of the Duchess of Cambridge has as its centre stone a beautiful sapphire that is said to be valued at around $500.000.[/left]
How do you care for your sapphire?
You can clean your sapphire using a soft cloth or brush and warm soapy water. Be sure to rinse it well to remove soapy residues. Don’t expose your gemstone to extreme temperatures, as sapphires can change colour when subjected to extreme heat. Be careful how you store these gems, as although this gemstone is quite durable as well as hard it can be scratched by a diamond or can be damaged if you engage in an intense physical activity. When removing jewellery, please don’t pull from the stone because you can weaken the setting.
Interesting facts about sapphires
Sapphire is the birthstone for September and is also associated with Thursdays. It symbolises sincerity, truth and faithfulness, and was to have curative properties and to protect against evil spells. The ancients regarded star sapphires as powerful talismans for protecting travellers.
Of the 30-40 most popular coloured gemstones, rubies and sapphires represent 50% of the total world sales.
Whereas the colour of some topaz, morganite, tanzanite and amethyst may fade over time and due to exposure to light, the colour of a natural sapphire or ruby will be as bright and vivid 50 million years from now
In some areas of rural Sri Lanka, heat treatment is still done in a traditional way using a blowpipe. By blowing it twice per second, the temperature can rise to above 1400°C.hu
If a sapphire appears black in room light at night then is poor quality.
*All images are from pinterest.com