Citrine, Chrysoberyl, Aquamarine

Citrine : Probably the commonest of all minerals on earth. It belongs to the quartz family and its common name is Silica ( Silicon oxide- SiO2). Much of the dust blowing in the wind consists of Silica and is also that which goes into the manufacture of glass. It is probably found in every corner of the earth.
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The most desirable of the Silica group is the Yellow and Golden Yellow varieties and most of the cuttable variety comes from Brazil where it is found in primary deposits sometimes in the form of huge rocks. Citrine is also found abundantly in gem qualities in Sri Lanka, India, Thailand, Burma, Madagascar, Columbia, USA, Nigeria, and Tanzania.
Citrine (and most varieties of quartz ) exhibit a unique property in that it oscillates at a constant frequency when subject to an electric charge and this property is applied in many critical industrial uses. In order to make the best use of this property the crystals would have to be untwined and pure. It was found that it was easier and cheaper to produce such very clean crystals synthetically rather than look for it in the natural variety. Therefore a large synthetic quartz industry developed to meet this need. The less pure ‘waste’ from this industry, not coming up to the electronics industry specs. (Still considerably pure ) was fed into the gem trade where the clarity or purity was less critical. The trade was now faced with a rather difficult problem in that it was extremely difficult, expensive and cumbersome to identify and separate the extremely clean synthetic quartz from the natural variety so much so that it was now desirable to have citrine with inclusions rather than the opposite because these inclusions was a sure way of identifying the natural.

One notable fact to be borne in mind is that very often, in fact far too often, many jewellers either through ignorance or with the intention of cheating, offer Golden (quartz) Citrine as Golden Topaz. The two have nothing in common and the prices are enormously different.

Due to the fact that citrine is a rather cheap gem it is put to a variety of uses such as carvings, household ornaments etc.

Chrysoberyl : This is a double oxide of Beryllium and Aluminium and until recently was found only in the yellow, brown and lemon green colours but lately fine leaf green and bright yellow (rivaling the colour of yellow sapphires) specimens have been found in Madagascar. Chrysoberyl is also found in Sri Lanka, India, Burma, Thailand, Brazil, Zambia Rhodesia and Tanzania.

The Chrysoberyl when packed with short needles parallel to the vertical axis can be cut en-cabochon to reveal a single streak that moves in the direction of light as the stone itself is rotated. This is referred to as a chatoyant effect and these stones are referred to as Chrysobery Cats-Eyes which also fall into the category of Phenomenal Stones. The best Cats-Eyes are those that have a finely defined streak that opens and closes from side to side without a break. The most desirable colour in Cats-Eyes is the honey colour .

The most coveted Alexandrite also a variety of Chrysoberyl. This stone which shows a rather unusual colour change, Strong Bluish Green in natural light and crimson red in incandescent light. The best Alexandrites to date are those found in the Ural mountains of Russia while fine specimens are also found, though less prolific in Brazil, India, Sri Lanka, Madagascar, Burma, Rhodesia, Tanzania and Zambia.

The Cats eye effect is also found in the alexandrite variety and this stone is called an Alexandrite Cats-Eye.

Aquamarine: This gem is a Beryllium, Aluminium silicate and belongs to the Beryl family (to which also Emerald belongs). The best colour as the name indicates is the colour of clear, tropical sea water or the colour of the clear sky. The more intense the colour the better it is while a greenish or yellowish tone would detract from its quality.

Some Aquamarines showing a greenish tone can be heat treated to get rid of this unwanted colour giving gems of a fine blue.

An Aquamarine catseye is also found though not common.

Large pieces of aquamarine are found in Brazil, perhaps the most prolific country for this type of gems while smaller pieces are found as rolled pebbles in Madagascar, Nigeria, Sri Lanka, India, USA, The Urals in Russia, /div>