Gemólogos.

                       C.C.C.T Tamanaco, Pirámide Invertida, Piso 3, oficina 323-A Chuao- Caracas, Venezuela.

TelFax: 0212-959.39.95 Cel. 0416-6325802

www.escueladegemologiaamericana.com   E-mail: auragod@cantv.net

THE EMERALD

By Aura Godoy.

Poetic and dreamy word, it is the name of perhaps the most beautiful precious stone.
May is the month of flowers, it is the month of Mothers and it is also the month of the most esteemed and expensive beryl, the emerald.
The family is the beryl and the variety is the emerald. It is an aluminum silicate with beryllium (Be3Al2 (Si3)6), whose green color is caused by trace: of chromium oxide or vanadium oxide impurities. It crystallizes in the hexagonal system. Its hardness is 7,5 on the Mohs scale.
The emerald’s beautiful green color has fascinated man the most remote eras. Its color symbolizes the beauty and promise of nature in each year’s spring. It is also a symbol of hope, kindness and virtue.
The Romans used to attribute to it medicinal powers for the cure of the eye tiredness. It is said that Nero used to refresh and restore his eyesight by looking thru the crystal of beautiful emerald.
Although it was already known in Ancient Egypt, the most beautiful pieces didn't’t reach Europe until after the Discovery of America.
The emerald has always been included in the list of precious stones. Its color varies between a light and dark green. It is of hydrothermal origin. It is present in rocks that are generally composed of lime stones or micaceous metamorphic rocks.

PRINCIPAL DEPOSITS:

Antiquity’s best known emerald deposits were located in Egypt, in the famous mine of Yabarah, they had a pallid tone.
During the Roman Era and the middle Ages, the deposits mined were in the Austrian valley of Habachthal.
At the present time, the most important deposits are located in Colombia, Russia, Brazil, Transvaal, Tanzania, Zambia and during the last few years, in Pakistan.
Colombia is the country from where the most beautiful pieces and the larges production always come from. The Colombian regions where deposits are located are:
MUZO: produces the emeralds with the best colors, they are a deep velvety green with a light yellow tone.
CHIVOR: produces stones with are mostly free of inclusions, with a somewhat blueish tone less intense that those from Muzo.

Other deposits are Cosquez, Gachalá and Peñas Blancas.
The Russian or Siberian emeralds have a yellowish- green color. They are more included and with a lighter tone than Colombians.
Brazil’s emeralds are generally classified as “green beryl”, the best ones are mined in the Itabira region.
The Rhodesian (Sandawana) ones have a sufficiently acceptable quality but because they are very included it is difficult to find cut gems with a weight of more than 1/3 karat.
Tanzania’s emeralds, up to 8 karats, have a quality very similar to that of Colombian ones.
Zambia’s always having a grayish tint.

CUTTING STYLES:

The cutting of this valuable gem requires the services of a professional cutter with great skill and a vast amount of knowledge plus, he must be a good observer, with great ability and patience since one mistake can change a gem’s value considerably. He or she is the one who will display all the beauty hidden inside the emeralds.

The cut which is used the most is the rectangular one, or the emerald-type cut. The table is usually quadrangular or rectangular. It has three scales of facets in the crown and there in the pavilion, parallel to the belt. They also have facets in the corners.
The gems that are very included and little transparency are cut cabochons.
Since the color in the crystal is not uniform but it is one of the most important elements to determine an emerald’s price, a high percentage of these gems have irregularities in the pavilion, since the cutter tries to fix the stone’s axis on the side where it presents its best color, so as to achieve for the mass to keep- by reflection- the most uniform green color.

“care needed in cutting.”

During the cutting process, it is necessary to avoid the stone’s overheating, heat can develop small fractures and in extreme cases, the gem can break. The same care has taken when jewelry made with emeralds is being cleaned or manufactured.

NATURAL EMERALDS FROM SYNTHETIC ONES.

Being precious stones of a high monetary value – there are optimum quality stones with a size larger than five carats that are worth fortunes – their identification cannot be done based on experience, because there are in the market synthetic gems that are very similar to the natural ones and imitations so perfect as to confuse any person, except a gemologist, who beside his knowledge, has the necessary instruments to tell the difference. His service is indispensable in every business related to the jewelry field.

To differentiate an emerald from any imitation or natural gem of the same color, it is essential to analyze the physical and optical properties, such as, specific gravity, refraction index, and fluorescence (this gives us the separation).

Distinguishing a natural emerald from a synthetic one (a synthetic emerald is manmade but it has similar physical and optical characteristics to the natural ones) requires more time and the other are equal; they can only be taken as indicators. Fluorescence, for example, is a comparative element; almost all synthetic emeralds present a strong ones are generally inert or yellow in fracture zones filled with oil.