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How To Choose a Sapphire
So What Is A Sapphire?
Is an exquisite deep blue sapphire your favourite gemstone? If you are looking for a special gift of jewelry, you will know that there are many beautiful gemstones out there to choose from. However, a high quality deep blue sapphire is very hard to beat.
So if you are looking for that unique and special engagement ring, or a stunning necklace or bracelet, then these beautiful blue gems are a great choice. They have been known since ancient times and their name comes from the Greek ‘sappheiros’ meaning ‘precious stone’. They rank as one of the four precious gemstones along with diamonds, rubies and emeralds, and top quality sapphires with few flaws and a deep, beautiful colour are rare.
So what are they? They are a variety of the mineral corundum, which is an aluminium oxide. When we think of these gems we generally think of them as a deep blue colour, but traces of the minerals titanium, iron, or chromium can colour them yellow, pink, orange, green or purple. If the corundum is coloured red the gemstone is known as a ruby and pink-orange corundum form the sapphires known as padparadscha.
Padparadscha come mostly from Sri Lanka and are very rare and extremely highly valued. The name padparadscha comes from the Sanskrit/Singhalese ‘padma raga’ meaning ‘lotus colour’, and a fine padparadscha can fetch as much as the best quality blue sapphire.
How Are They Valued?
They are a very hard gemstone and apart from being used in jewellery, they are also used in infrared optical components, high-durability windows, wafers for the deposition of semiconductors and as watch crystals.
How much you will have to pay for one will depend on its colour, clarity, size, cut, quality and where they were mined. There are large deposits found in Sri Lanka, Madagascar, Thailand, Eastern Australia, the United States and East Africa, but it is the ones from Burma and Kashmir that are the most highly valued for their deep colour and clarity.
They are often found in the same deposits as rubies, but usually one of the gemstones is more prevalent than the other. Due to their value and rarity, these precious stones tend to be cut into ovals and cushions as these involve cutting away less of the original rough gemstone. The popular round shape generally involves removing a lot of the rough; hence round sapphires tend to be very expensive.
Hue, Saturation & Tone
When you are looking at colour it is broken down into hue, saturation and tone, and the overall grade of your gemstone is gauged by looking at these attributes. The grades are Poor, Fair, Good, Very Good and Exceptional. Hue is the ‘colour’ of the sapphire, saturation refers to the brightness of the hue and tone is whether the hue is lighter or darker.
Blue sapphires are judged on the purity of their primary hue. They do contain small amounts of other colours and purple, violet and green are the normal secondary hues to be found in one. It is considered that purple and violet can enhance the beauty of the blue colour in this gemstone, while green detracts from the colour. A fine quality blue sapphire normally has no more than 15% violet or purple secondary hues. These precious stones can also have what is known as a mask and with blue sapphires, gray is the usual mask found that reduces the saturation or brightness of the gemstone.
Star and Colour Change Sapphires
You can also get a special type of gem known as a ‘star sapphire’, which is one that displays the phenomenon known as asterism. Asterism is caused by fine needle-like rutiles or inclusions in the gemstone that make it seem as though a six-pointed star is visible in the precious stone when it is viewed with a light overhead.
The more intense the ‘star’ appears, the more the star sapphire will be worth. There is also a rare type known as colour change sapphire. These amazing gemstones appear to be different colours in different lights. They mainly come from Tanzania and can shift from blue to purple, or pink to greenish depending on whether they are viewed in daylight or under artificial lighting.
These gemstones are frequently treated to improve their clarity and colour. They are commonly heat treated which involves being heated to high temperatures for several hours or being heated in a nitrogen-deficient atmosphere oven for as long as seven days. There is evidence that this practice goes back as far as Roman times, and high heat treatment removes a lot of the ‘silk’.
They are also subjected to diffusion treatments where elements are added to the gemstone to alter or improve the colour. Beryllium is most commonly used, and when diffused into a sapphire under intense heat it will produce gemstones in a variety of colours other than blue, most notably orange. Natural, untreated sapphires are fairly rare and when you purchase them they should come with a certificate to state that they have not been treated. Likewise, diffused sapphires should be cheaper to purchase and you should be told that the gemstone you are buying has been subjected to diffusion.
History & Traditions
They have been worn since ancient times and have a long history and many traditions associated with them. In ancient Persia it was believed that the world rested on an immense sapphire and that it was the reflection of this huge stone that caused the sky to be blue. Traditionally it was thought that the tablets that held the Ten Commandments in the Old Testament were made from sapphire that was so strong that it could not be smashed even by a large hammer.
Also the seal-stone in the ring of King Solomon was said to have been a sapphire. Among Buddhists, it is regarded as the Stone of Stones giving spiritual light and is thought to bring a desire for prayer. Buddhists also believe that they bring peace and happiness as long as the wearer leads a pure and moral life. During the Middle Ages in Europe they were worn as protection against poison, fevers, plague, and skin diseases. They were also believed to be a powerful talisman against Black Magic and were thought to encourage chastity.
It is the birthstone for the month of September and it symbolises faithfulness and sincerity. They are also believed to have healing and calming properties. They are also often used in crown jewels to symbolise a wise and pure ruler. Also, the 45th Wedding Anniversary is known as the Sapphire Anniversary, and gifts of this precious stone jewelry are often given to celebrate.
There are many famous sapphires known around the world today. The Star of India is believed to be the world’s largest star sapphire. This amazing gemstone was mined in Sri Lanka and was given as a donation to the American Museum of Natural History in New York in 1900 by the wealthy banker J P Morgan.
The Star of India is regarded as being almost flawless and unusually displays the asterism on both sides of the stone. The Star of Bombay is also very large at 182 carats and is in the National Museum of Natural History in Washington DC. The Logan Sapphire was named after Mrs John Logan who donated the precious stone to the Smithsonian Institute in 1960. It is the second largest blue sapphire known and weighs 423 carats. It is cushion-cut and set in a brooch surrounded by 20 round brilliant cut diamonds.
So while you are choosing your sapphire jewelry have a good look at the colour, clarity, cut and carat and also ensure that you get a certificate if you are buying a natural, untreated gemstone. Whether you opt for the traditional deep blue or a fancy stone in yellow, green, purple or pink, you will know that you have bought a unique and beautiful gemstone with many traditions and a long history behind it.
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