Essential Guide To Sapphire Gemstones

By Author: Alexandra
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From the deep blue of the evening sky to the fresh mid-blue of a brilliant summer's day, the unforgettable sapphire has captivated jewellery enthusiasts for centuries. In fact in early times, some people even believed that the firmament was an enormous blue sapphire in which the Earth was embedded.
The following guide will give you an interesting look into the ins and outs of these stunning gemstones, so you can make a more informed choice when shopping around for that perfect sapphire ring, necklace or set of earrings.
Origin & Supply of Sapphires
The word sapphire originated from the Greek name sappheiros, meaning "blue stone". This royal gem is part of the mineral corundum family, an aluminium oxide, which is harder ((9 on the Mohs scale) than most other stones, it is only exceeded in strength by diamonds.
Sapphires are found naturally within earth sediment (being so hard they are resistant to erosion) and rock formations. Synthetic sapphires have also been under manufacture since 1902, but these are used for industrial or decorative purposes rather than in jewellery.
Natural sapphires ...
... are mined from alluvial deposits or underground workings. Some of the main mining locations include Madagascar (the world leader in sapphire production since 2007), Burma, Sri Lanka (the first recorded location in history), Australia, Thailand, India, Tanzania, Kenya, China and Montana (North America).
As with all gems, the cost of natural sapphires varies depending on their colour, clarity, size, cut, overall quality and geographic origin.
Colour and Treatment
Colour in gemstones breaks down into three components: hue, saturation (brightness) and tone (lightness to darkness).
Although they are mainly known to be blue, in fact sapphires occur in many colours ranging from colourless to black. As part of the corundum family of minerals, the term "sapphire" automatically indicates the blue variety. Any other colour except red (in which case it is then a ruby) will have a prefix, such as "yellow sapphire". It is trace amounts of other elements such as iron, titanium, or chromium that give sapphires their alternate colours.
Like most gemstones, sapphires may be treated by several methods such as heating (used since Roman times) to enhance and improve their clarity and colour.
Un-heated stones are fairly rare and will often be sold accompanied by a certificate from an independent gemmological laboratory confirming "no evidence of heat treatment". An example is Yogo sapphires – these often do not need heat treatment because their cornflower blue colouring is uniform and deep, they are generally free of inclusions, and they have high uniform clarity.
Main Types of Sapphire Gemstones
Blue Sapphires
Blue sapphires are evaluated according to the purity of their primary colour, while purple, violet and green are the most common secondary hues found in them. Violet and purple tones can add to their overall beauty, but green tones are considered to be decidedly negative. In addition, gray is the normal saturation mask found in blue sapphires, but if prevalent it will reduce the gemstone’s brightness so this is also something to steer clear of.
As a yardstick, blue sapphires with up to 15% violet or purple tones are generally thought to be of fine quality. The colour of high quality blue sapphires can be described as a vivid medium dark violet to purplish blue, where the primary blue hue is at least 85% and the secondary hue no more than 15%.
Different Coloured Sapphires
Yellow and green sapphires are commonly found, while a deep pink sapphire (caused by increased chromium levels) will boost its value as this will then tend to the red colour of rubies.
You can also find sapphires in shades of orange and brown, as well as the colourless variety which is sometimes used as a diamond substitute in jewellery.
Padparadscha sapphires are the name given to pink-orange corundum and they are relatively rare. Originally mined in Sri Lanka, they also naturally occur in Vietnam and parts of Africa. They have a low to medium saturation and light tone.
Colour change sapphires are even rarer – they are unusual as they reflect different colours in different lighting, ranging from blue and purple to pink and green hues. The gem gravels of Tanzania are their main source.
Star Sapphires
These types of sapphires are aptly named because they grow with needle-like inclusions following the underlying crystal structure that cause the appearance of a six-rayed star. Twelve-rayed stars are also occasionally found, as well as those with parallel whisker inclusions which produce a "cat's eye" effect
Conclusion
The durability and unforgettably brilliant beauty of sapphires has inspired jewellery enthusiasts since ancient times. From glistening sapphire rings and earrings to intricately designed necklaces, these gorgeous gemstones never fail to impress.
About the Author: Julia Littlewood is a stylist and enthusiast of sapphire rings.