Chrysoberyl Gemstones - Beryl group of gemstones
Introduction
Chrysoberyl is a true miracle from Mother Nature, as far as gemstones are concerned; this is a gemstone that is characterized by a feature known as Chatoyancy, or having a cat´s eye, making it look like the wearer is wearing the eye of a cat. This gemstone is the one that truly deserves to have the name Cat´s Eye, since it is also yellow in color, resembling the eye color of a cat. This gemstone is a marvel to look upon with a narrow shaft of light, against a background of shimmering yellow, which seems to move across the surface of the stone as it is moved. Although this feature is shown by other gemstones, the name of the gemstone has to be appended, e.g. The Quartz Cat´s Eye; Chrysoberyl is simply called the Cat´s Eye.
Chrysoberyl is, by nomenclature, mentioned in the same breath as the beryl group of gemstones with the most popular representatives being the emerald and aquamarine. The name Chrysoberyl is derived from the Greek word which means "Gold-colored beryl" which truly described this gemstone. Chrysoberyl forms an independent gemstone group, just like the alexandrite, although the alexandrite is considered the more attractive of the two; despite this, it is only the Chrysoberyl which can truly lay stake to the name cat´s eye.
Chrysoberyl, from a mineralogical aspect, is an aluminum oxide which has traces of beryllium, and due to this, it is not related to the beryl, which is actually a silicate. The Chrysoberyl has a hardness value of 8.5 on the Mohs scale, making it very hard and this ideal for use in making jewelry. Chrysoberyl has color tints that range from lemon to greenish yellow, and also honey colors; it also has shades that range from mint green to brownish green, and they are mainly found in Sri Lanka, Brazil and East Africa.
Positive energy and protection
In ancient civilizations, the owners of Chrysoberyl were said to be protected from all forms of disaster. They took the cat´s eye as a very effective talisman and protective stone, which could ward of any forms of danger. Since this is a gemstone that has particularly gold tints, it is said to give the wearer access to wealth. This is a notion that was grounded in fact, since this wonderful gemstone, as one of the purest forms of cat´s eye gemstones, is very high up in the gemstones associated with style and class.
Chrysoberyl is also said to be associated with self-control and discipline, when it comes to modern gemstone therapy practices. They are believed to imbue the wearer with the ability to learn and concentrate better, and also provide clear vision and far sight regarding various situations. People believe that this is a stone with secret powers which could be used to turn negative thoughts into positive ones. This is also a gemstone that is believed to have more powers when the effect of the cat´s eye is pronounced. This is a gemstone that is, however also associated with brining about harmony and tolerance in relationships. For those who are born in the zodiac sign of Leo, this is considered to be a lucky stone.
The magic that is the cat´s eye
There are very few deposits in the world where you can find genuine Chrysoberyl cat´s eye gemstones, so is the case with other forms of this wonderful gemstones. It was unimaginable that there would ever be a gemstone that would actually blink like the eye of a cat, and in such a natural manner. People wondered whether it was natural, or whether it was magic. They also wondered what could be giving the gemstone the ability to wink like a cat; a feature that is irresistibly beautiful.
After careful study of the crystal nature of the gemstone, scientists have attributed this characteristic to the presence of very fine inclusions, deep in the structure of the stone. The light enters the stone and is reflected off these inclusions, which makes a fine strip of light to be seen, which runs in a perpendicular direction of the inclusions, an affect that is similar to the eye of a cat. This strip of light tends to glide across the surface of the stone whenever it is turned against the light. This is a phenomenon that is known as Chatoyancy, which is derived from the French name for a cat, "Chat". There are Chrysoberyl gemstones which do not exhibit the cat´s eye effect, and these are usually facetted into gems, but those that have Chatoyancy are cut into cabochons which bring out this effect properly.
The Chrysoberyl is a beautiful gemstone, and it is very popular, with colors ranging from honey-colored to mint green. Due to these features it is valued highly by gemstone lovers and aficionados all over the world. The cat´s eye is the most attractive variety of Chrysoberyl and it is very valuable especially to those who are familiar with gemstones. The value of the Chrysoberyl, just like with any other gemstone, is based on the clarity, beauty and color of the stone. The depth of color is a very important factor since it affects the Chatoyancy of the gemstone. For anyone who would like a Chrysoberyl that has a deep color and very fine line of marked eye-line, he or she should be ready to pay a very hefty price for it; this is because the beauty and marked appearance of the cat´s eye also determines the price.
When you are purchasing this gemstone, you must pay particular attention to the appearance of the "eye". It should be such that the line passes through in a narrow band of light, so that it is clearly marked. When you have fine specimens of this gemstone, the effect seems to open and close, and the stone seems to be winking at you. They should always have a distinctive color, and should be as transparent as possible. Those that are precious are those with clear honey yellow and fine green tones in color.
Among the beautiful things that Nature has produced, Chrysoberyl cat´s eyes can be said to be most fascinating. This is a gemstone that will pull your eye to this effect over and over again, and you will never tire of seeing this. The effect is said to bring about enthusiasm and zeal when you are looking for something unique. These gemstones are particularly suited to be worn as rings by men, and this is a testament that Man has always been seduced by the effect of the cat´s eye.
Chrysoberyl has an interesting feature which is called Trillings, whereby the crystals are arranged in cyclic twins. The twinned crystals form in a hexagonal structure, and are usually the result of three twins, with each bearing an angle of 120 degrees to its neighbor.
There are three main types of Chrysoberyl gemstones, and these are the ordinary yellow to green Chrysoberyl, the cat´s eye, which is also called Cymophane, and Alexandrite. The yellow green Chrysoberyl was also called the Chrysolite, during the Victorian and Edwardian eras; this brought a lot of confusion, since the name was also used for a mineral known as olivine, which is called Peridot when used as a gemstone. In the gemological world, the name Chrysolite is no longer used.
Cymophane
The true Chrysoberyl cat´s eye is called Cymophane, and it exhibits an opalescence or Chatoyancy that reminds one of how the eye of a cat looks like. When this stone is cut into a cabochon, it gives off a light green color, which as a silly shaft of light that extends across the top of the stone like the eye of a cat.
The occurrence of Chrysoberyl gemstones
Chrysoberyl gem is formed through the pegmatitic process where the earth´s crust melts and produces molten lava at low density, which slowly rises to the surface. When this body of magma cools down, water, which was there in low concentrations slowly becomes more concentrated inside the molten rock, since it could not be included in the solid minerals as they crystalized. The magma left behind has higher levels of water, and also rare minerals, which were also excluded in the crystallization of the major rocks as they formed. This water, then transfers that temperature range towards the bottom, before the magma can fully solidify, allowing the concentration of these rare minerals to increase to the point where they now form their own distinct and different minerals. This then forms igneous rocks, which are formed at low temperatures from a melt that is rich in water. These rocks contain large crystals of some common minerals such as feldspar and quartz, and also high levels of rare minerals such as lithium, niobium and beryllium, which now form other minerals which are now called pegmatite. The high concentrations of water in the magma is the one that allows for the crystals to grow quickly, and this is the reason why pegmatite crystals are usually large in size, and this is how these wonderful gemstones are formed.
Country rocks which are found near pegmatite formations can also allow for the growing of Chrysoberyl; this happens when the fluids from the pegmatite, which are rich in aluminum and beryllium, react with minerals in these surrounding rocks. This is the reason why Chrysoberyl can also be found in mica shists and also in contact with metamorphic formations of dolomite marble. The fact that Chrysoberyl is a hard mineral which does not weather easily, chemically, makes it possible for the Chrysoberyl to be washed out of the rocks and deposited in the sands of rivers, and also in alluvial deposits with other gemstones such as diamonds, corundum, spinel, garnet, topaz and tourmaline. The Chrysoberyl found in these places is usually round is shape, as opposed to the sharp edges of that found in pegmatite. Most Chrysoberyl is found in Sri Lanka and Brazil, and is usually found from placers, since the host rocks are highly weathered or eroded.
When the fluids in the pegmatite are rich in beryllium, it is possible for either beryl or Chrysoberyl crystals to form. If the ratio of beryllium is higher than that of aluminum then beryl is formed; if the ratio has a high concentration of aluminum, the Chrysoberyl will form. Both are found to be stable with the mineral quartz. In order to get alexandrite, there should be some chromium present in these fluids. Beryllium and chromium rarely occur in the same rock formations; chromium is found in mafic and ultramafic rocks, where you can rarely find beryllium. Beryllium is found mainly in felsic pegmatite, in which chromium is almost always absent. This means that there is only the possibility of alexandrite to grow where the pegmatite fluids are rich in beryllium, which reacts with the chromium in the country rock. This is the main reason why Chrysoberyl is a very rare gemstone.
In summary
Cymophane, or cat´s eye is the term that is given to the Chrysoberyl variety that has a translucent, yellow tinted Chatoyancy. The name Cymophane comes from the Greek words which mean "having a wavy appearance", which is because of the haziness, which causes the visual distortion of light, that would normally seem to be well-defined on the surface of cabochons. This is an effect that can be mixed with the effect of the cat"s eye which the stone normally has. This is a variety that has very small, microscopic cavities, or needle-shaped inclusions, which are rutile in nature, and have a parallel orientation to the main axis of the stone. These inclusions are the ones that produce a single ray of concentrated light, which passes across the crystal like the eye of a cat. For this effect to be seen to its best, the stone has to be cut into a cabochon which is perpendicular to the c-axis. The Chrysoberyl yellow color is brought about by the presence of iron 3 ions.
There are other minerals, such as scapolite, corundum, spinel, tourmaline, and quartz also exhibit the cat´s eye effect, which seems similar to that of Cymophane, the gemstone world has to add the name of the gemstone in question, leading to names such as the quartz cat´s eye, or ruby cat´s eye, etc. it is only Chrysoberyl which is given the single name "cat´s eye" without any other designation being added to it.
There are Chrysoberyl gemstones that do not have the tiny inclusions which cause the cat´s eye effect, and these are usually cut into faceted gemstones. The alexandrite cat´s eye is one which changes color. The best cat´s eye gemstones are termed as being milk and honey. His is an effect that refers to the milky ray of white light that passes across the center of the cabochon as a single ray of light along the length of the cabochon, and this ray is overlaid on the yellow background of the stone. The honey color is considered to be exhibited by the best quality of Chrysoberyl that you can ever find; however the yellow colors are also considered highly and are popular. Whenever Chrysoberyl is found, only a small percentage of the stones mined will have this cat´s eye effect.
It is at the end of the 19th century that the cat´s eye Chrysoberyl became important. The Duke of Connaught presented a ring with a cat´s eye effect as an engagement present; this event propelled the stone into famedom, and it became more popular, and its value increased exponentially. Before that time, the cat´s eye Chrysoberyl was usually seen in gemstone and mineral collections and not on rings and other adornments. This increase in demand brought about an increased search for the gemstones in Sri Lanka.
Basically, the Chrysoberyl is a gemstone that is very versatile as a jewelry piece. It is quite hard and also beautiful. This means that the ring can be worn every day, giving the wearer an aura of style, without the wearer worrying that the stone will become damaged. The term Chrysoberyl can be applied to three different types of gemstones, of which the alexandrite and true cat´s eye are a part of. The ordinary Chrysoberyl has a yellow-green appearance and does not have many inclusions and therefore does not show the cat´s eye effect. This is the reason why it is cut into faceted stones so light can shine through and bring out its brilliance, which can almost meet that of a diamond.
