For centuries, sapphire has been prominently featured in jewelry. Its hardness, stability, and toughness make it suitable for all types of jewelry. Sapphire’s endless shades of blue have made it one of the most popular gems around the world.
Sapphires are gaining more and more love and attention among jewelry-lovers today. Is it after the gorgeous engagement ring of Princess Diana which 12-carat oval blue Ceylon sapphire is now shining on the finger of Kate Middleton?
Whatever the reason, sapphires become more and more popular choice for all types of jewelry, not limiting to engagement pieces. It is not surprising, because they come in many types of colours – all shades of blue, red, pink, yellow, green, etc. The most sought after fancy coloured sapphire is the orangey pink variety known as Padparadscha, which means ‘lotus flower’ in Sinhalese. The non-professional would easily confuse the non-coloured sapphire with a diamond.
The most important sapphire deposits are found in Sri Lanka, Myanmar, and Thailand. Other producing countries include Australia, Cambodia, and the Unites States.
Advanced laboratory testing can help determine the geographic origin of some sapphires. Certain geographic origins such as Kashmir can have a significant impact on the gem’s value. It is important to note that the term ‘Kashmir’ is used in two different ways in the trade. In some contexts it is used to indicate that the origin of the sapphire is the famed deposits of Kashmir known for their exceptional quality gems however, it can also be used as a descriptive term meaning that the blue of a certain sapphire is reminiscent of the rich hues seen in sapphires from Kashmir.
The heat treatment
Sapphires are routinely treated to improve their appearance. Different heating temperatures and conditions can produce a vast array of results: dark stones can be lightened, light stones can be darkened, inclusions can be dissolved to improve the clarity, and inclusions can be introduced creating star effects. These treatments are stable and many can also be used to improve the appearance of fancy coloured sapphires.
Sapphires can also be treated using a process called diffusion. Pre-facetted gems are heated in an iron rich environment causing the iron to penetrate into the sapphire making it blue. Due to their size, the iron atoms can only penetrate the surface of the stone. Surface diffusion can also be performed on fancy colour sapphires such as yellow sapphires where nickel is used to enhance the colour. This treatment s not stable because the colour penetration is very shallow and will disappear if the stone is re-polished or re-cut. Gemmologists can easily identify this treatment.
There is another diffusion treatment called ‘bulk diffusion’ primarily used to improve the appearance of fancy coloured sapphires. This treatment uses beryllium (Be), a smaller chemical element that can penetrate the entire stone. Beryllium diffusion can produce many different colours including yellow, orange, and the orangey-pink hues of Padparadscha sapphire. This treatment is more stable than surface diffusion as the colour will not be removed if the stone is re-polished.
The gem trade considers heat treatments acceptable whereas diffusion treatments should always be disclosed at the point of sale.
Colour is the most important criteria for sapphire and although sapphire comes in virtually every imaginable colour it is the saturation or intensity of the colour that will determine quality and value. Pale or overly dark stones will have lower values while more vivid colours will have higher values.
A gem’s clarity will also have an impact on price. Most natural sapphires contain inclusions that are visible with magnification. Stones with fewer inclusions will appear brighter and more transparent and will have higher values.
The quality of the cut will have a significant impact on the overall appearance and value of the gem. A well-cut stone respecting the ideal proportions will display more brilliance than a poorly cut stone. Gems are sold by weight and often the lapidary (stone cutter) is faced with the difficult decision of producing a smaller perfectly cut gem or a larger stone of average cut quality. Poorly cut stones often show an effect called a ‘window’ where it is possible to see right through the gem because the light and the colour are not being optimally reflected back through the table.
Large rough sapphire crystals are very rare and therefore large facetted stones are also rare. This rarity contributes to the higher prices of large high-quality sapphires.
Market trends, personal preferences, and geographic origin can also play a role in the value of sapphire and fancy coloured sapphires.
Traceable and ethically-sourced sapphires
Jewelry specialists agree that it is partucularly difficult to provide fully traceable choices of stones. You often know the country where the stone is cut but, unless you go directly to the mine and observe the whole way of the stone you can’t be completely sure that it did not get there from another place, which is in the middle of a conflict zone. Obviously, the suppliers who want to provide their clients with ethically-sourced stones, need to do a lot of work.
Let me show you how you can trace a sapphire. This is an ordinary adventure of Pierres des Charme, providing traceable sustainable Montana sapphires.
1.The mine (Montana, USA)
A big nice lot of rough, uncut sapphires is bought directly from the Rock creek mines of Montana.
2. The heat treatment and cut (Sri Lanka)
In 90% of cases, sapphires are heated in order to improve their colour or purity. This treatment is fully accepted in the industry, provided that no external elements are added to the process; especially since soil can have that same effect on the gemstones. Some countries are experts in this area. Sri Lanka is one of them. The uncut gemstones are sent out there so they could be heated and cut.
The cutting factory that cuts the sapphires is located near Colombo, they hire about eight workers, women and men. No children. Working hours are from 8 am to 4.30 pm. In December, everyone gts double pay. Most employees have been working for the company since its founding eighteen years ago.
The employee retention rate is excellent there, as owners treat workers like members of their own family. For example, they’ll help them out in buying their house with interest-free loans. They’ll also offer support for wedding or funeral expenses. Once, they even went on vacation all together for three days. With spouses and children as well! All-inclusive. The mood at the cutting factory reflects this family atmosphere.
The gemstones are preformed and then heated in a most rudimentary place. Overnight, the temperature is maintained at 1,850 degrees Celsius with oxygen supply (through all visible pipes). Then the temperature is gradually reduced. It may take three days for total cooling and it is only then that the colour of the gem is stabilized.
Stones are often heated again two or even three times, then they are cut.
This is where the expertise of the “burning man” comes into play. Montana sapphires do not react in the same way as the ones from Sri Lanka. The end result is impeccable and beautiful.
After this cutting and heating process, the final yield is down to 20% of the initial number of uncut gems.
Then they have to be sorted according to their shape, size and colour in order to determine the best selling prices. A very small number of uncut stones were fairly pure and good-coloured, and therefore did not need to be heated.
This is a long adventure of your ethically-sourced, traceable sapphire! It is not just a sparkle thing that will get in your ring. It is the beauty, work and energy of many countries, whose nature and people took part in creating the stone!
Photos and information: Pierres de charme