More Gemstones

More Gemstones…

Diamond

DiamondsThe hardest, rarest, densest natural substance known to man. A precious gemstone composed of pure Carbon. A diamond’s quality is rated in accordance with the Four C’s: Cut, Color, Clarity and Carat Weight. While Africa is known as the Diamond continent, it is actually in Australia that the largest reserves are to be found – including the very rare and highly valued pink and red fancy colored diamonds Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history. Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns. They are commonly judged by the “four Cs”: carat, clarity, color, and cut. Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could then be found many centuries ago along the rivers Penner, Krishna and Godavari. Diamonds have been known in India for at least 3000 years but most likely 6000 years.The name diamond is derived from the ancient Greek ?d?µa? (adámas), “unbreakable, untamed”, from ?- (a-), “un-” + daµ?? (damáo), “I overpower, I tame”, and is the real-world origin of myths about a superhard metal called adamant.

In 1813, Humphry Davy used a lens to concentrate the rays of the sun on a diamond in an atmosphere of oxygen, and showed that the only product of the combustion was carbon dioxide, proving that diamond is composed of carbon.[8] Later, he showed that in an atmosphere devoid of oxygen, diamond is converted to graphite.The most familiar usage of diamonds today is as gemstones used for adornment, a usage which dates back into antiquity. The dispersion of white light into spectral colors, is the primary gemological characteristic of gem diamonds. In the twentieth century, experts in the field of gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are carat, cut, color, and clarity.
Diamond is the birthstone for the Month of April.
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Alexandrite

alexandriteThis rare gemstone is named after the Russian tsar Alexander II (1818-1881), the very first crystals having been discovered in April 1834 in the emerald mines near the Tokovaya River in the Urals. The discovery was made on the day the future tsar came of age. Although alexandrite is a relatively young gemstone, it certainly has a noble history. Since it shows both red and green, the principal colors of old Imperial Russia, it inevitably became the national stone of tsarist Russia. Beautiful alexandrite in top quality, however, is very rare indeed and hardly ever used in modern jewelery. In antique Russian jewelery you may come across it with a little luck, since Russian master jewelers loved this stone. Tiffany’s master gemmologist George Frederick Kunz (1856-1932) was also fascinated by alexandrite, and the jeweler’s firm produced some beautiful series of rings and platinum ensembles at the end of the 19th and beginning of the 20th century. Smaller alexandrites were occasionally also used in Victorian jewellery from England.

 The most sensational feature about this stone, however, is its surprising ability to change its color. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. This unique optical characteristic makes it one of the most valuable gemstones of all, especially in fine qualities. Alexandrite is very scarce: this is due to its chemical composition. It is basically a chrysoberyl, a mineral consisting of colorless or yellow transparent chrysoberyl, chrysoberyl cat’s eye and color-changing alexandrite (also in cat’s eye varieties). It differs from other chrysoberyls in that it not only contains iron and titanium, but also chromium as a major impurity. And it is this very element which accounts for the spectacular color change. Rarely, vanadium may also play a part. According to CIBJO nomenclature, only chrysoberyls displaying a distinct change of color may be termed alexandrite.
Alexandrite is the Birthstone for the Month of June
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Peridot

PeridotThe vivid green of the peridot, with just a slight hint of gold, is the ideal gemstone colour to go with that light summer wardrobe. No wonder – since the peridot is the gemstone of the summer month of August. The peridot is a very old gemstone, and one which has become very popular again today. It is so ancient that it can be found in Egyptian jewellery from the early 2nd millennium B.C.. The stones used at that time came from a deposit on a small volcanic island in the Red Sea, some 45 miles off the Egyptian coast at Aswan, which was not rediscovered until about 1900 and has, meanwhile, been exhausted for quite some time. Having said that, the peridot is also a thoroughly modern gemstone, for it was not until a few years ago that peridot deposits were located in the Kashmir region; and the stones from those deposits, being of an incomparably beautiful colour and transparency, have succeeded in giving a good polish to the image of this beautiful gemstone, which had paled somewhat over the millennia.

The ancient Romans too were fond of this gemstone and esteemed its radiant green shine, which does not change even in artificial light. For that reason they nicknamed it the ’emerald of the evening’. Peridot is also found in Europe in medieval churches, where it adorns many a treasure, for example one of the shrines in Cologne Cathedral. During the baroque period, the rich green gemstone once again enjoyed a brief heyday, and then it somehow faded into oblivion.
Peridot is the Birthstone for the Month of August
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Tourmaline

TourmalineTourmalines are gems with an incomparable variety of colors. The reason, according to an old Egyptian legend, is that the tourmaline, on its long journey up from the centre of the Earth, passed over a rainbow. In doing so, it assumed all the colours of the rainbow. And that is why it is still referred to as the ‘gemstone of the rainbow’ today. The name tourmaline comes from the Singhalese words ‘tura mali’. In translation, this means something like ‘stone with mixed colors’, referring to the colour spectrum of this gemstone, which outdoes that of all other precious stones. There are tourmalines from red to green and from blue to yellow. They often have two or more colours. There are tourmalines which change their color when the light changes from daylight to artificial light, and some show the light effect of a cat’s eye. No two tourmalines are exactly alike. This gemstone has an endless number of faces, and for that reason it suits all moods. No wonder that magical powers have been attributed to it since ancient times. In particular, it is the gemstone of love and of friendship, and is said to render them firm and long-lasting.

 In order to understand this variety of color, you will have to brush up your knowledge of gemmology a little: tourmalines are mixed crystals of aluminium boron silicate with a complex and changing composition. The mineral group is a fairly complex one. Even slight changes in the composition cause completely different colors. Crystals of only a single colour are fairly rare; indeed the same crystal will often display various colors and various nuances of those colors. And the trademark of this gemstone is not only its great wealth of color, but also its marked dichroism. Depending on the angle from which you look at it, the colour may be different or more or less intense. It is always at its most intense when viewed looking toward the main axis, a fact to which the cutter must pay great attention when lining up the cut. This gemstone has excellent wearing qualities and is easy to look after, for all tourmalines have a good hardness of 7 to 7.5 on the Mohs scale. So the tourmaline is an interesting gemstone in many ways
Tourmaline is the Birthstone for the Month of October
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Citrine

 

citrineLet’s suppose that someone has bought a moped, yet his friends and acquaintances keep talking about his ‘wonderful racing machine’. He surely feels confused, or feels that they are taking the mickey out of him. A moped was exactly what he wanted for short trips in good weather, but even the salesman said that he was now in possession of a ‘real flyer’. That’s roughly how things go with the citrine, the stone for the month of November. Many people have come to know and love this stone under the name gold topaz, or Madeira or Spanish topaz, although in actual fact it has very little in common with the higher-quality gemstone topaz – except for a few nuances of color. Thus the history of the citrine is closely interwoven with that of the topaz, and coincides with it completely when it comes to the interpretation of alleged miraculous powers. However, the citrine is a member of the large quartz family, a family which, with its multitude of colors and very various structures, offers gemstone lovers almost everything their hearts desire in terms of adornment and decoration, from absolutely clear rock crystal to black onyx. And it does so at prices which are by no means unaffordable.

The name is derived from the color – the yellow of the lemon – , although the most sought-after stones have a clear, radiant yellowish to brownish red. Like all crystal quartzes, the citrine has a hardness of 7 on the Mohs scale and is thus, to a large extent, insensitive to scratches. It won’t immediately take offense at being knocked about either, since its cleavage properties are non-existent. Even if their refractive index is relatively low, the yellow stones have just that mellow, warm tone that seems to have captured the last glow of autumn. Like golden Rhine wine or sparkling Madeira, heavy and sweet, citrine jewelery shimmers and brings a hint of sunshine to those dull November days.
Citrine is the Birthstone for the Month of November
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Blue Topaz

Blue TopazIt is a fluorine aluminum silicate and comes in yellow, yellow-brown, honey-yellow, flax, brown, green, blue, light blue, red and pink … and sometimes it has no color at all. The topaz. The topaz has been known for at least 2000 years and is one of the gemstones which form the foundations of the twelve gates to the Holy City of the New Jerusalem. These so-called apocalyptic stones are intended to serve in protection against enemies and as a symbol of beauty and splendor. It cannot be proved conclusively whether the name of the topaz comes from the Sanskrit or the Greek, though the Greek name ‘topazes’ means ‘green gemstone’. The Romans dedicated the topaz to Jupiter.

The color in which the topaz is most commonly found is yellow, and that is the color in which it occurs in one of the major German gemstone rocks, the Schneckenstein (a topaz-bearing rock said to resemble a snail) in Saxony. In the 18th century, it was mined there during a period of over 60 years. However, most of the crystals were hardly a centimeter in diameter. You had to go to Siberia or Brazil to find crystals as large as your fist. Having said that, anyone who is interested can convince himself of the beauty of cut specimens in the topaz set in Dresden’s Grünes Gewölbe (Green Vault). The enormous and magnificent topaz from the Portuguese crown, the Braganza, was for a long time thought to be a diamond. It weighs 1680 ct.. In mysticism, the topaz is attributed with a cooling, styptic and appetising effect. It is said to dispel sadness, anger and nocturnal fears, to warn its wearer of poisons and protect him or her from sudden death. It is reputed to make men handsome and intelligent and sterile women fertile and happy. However, it is probably better not to rely too much on its magical powers, since it was also claimed that you could immerse your hand in boiling water after a topaz had been thrown into it and retract it again unharmed!
Blue Topaz is the Birthstone for the Month of December
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