Emerald Story

Historical significance
Emeralds are green gemstones colored by a trace of chromium, which belong to the mineral species called beryl. The name emerald is derived from the Greek word Smaragdos which in turn was derived from a Persian word. However, Smaragdos referred to all green gemstones at that time.

An interesting historical fact about emerald is that it was considered the symbol of immortality and faith, and was dedicated by the ancients to the goddess of love—Venus. It is even said to be beneficial to the eyes (this may be related to the fact that green in general has a nice soothing effect on the eyes). The greenery around us also helps to refresh our eyes.

Physical and Chemical properties of Emerald
Color: Emerald green, light green, bluish green, yellowish green and dark green.
Moh’s hardness: 7.5 Moh’s hardness measure’s a gemstone’s resistance to surface scratches. Gemstones with a hardness of above 7 are reasonably resistant to surface scratches, making them more durable. Durability is one of the most important attributes of a gemstone.
Specific gravity: 2.7-2.8. The specific gravity (SG) compares the weight of a gemstone with the weight of an equal volume of water at 4ºC. This means that emerald is approximately 2.7 times heavier than an equal volume of water at 4ºC.
Transparency: Transparent to opaque.
Refractive index: 1.57-1.59 (DR=0.006-0.008). The R.I of a gemstone compares the speed of light in air to the speed of light in the gemstone. The R.I of a stone can be measured with the refractometer.
Chemical composition: Al2Be3(SiO3)6 Aluminum beryllium silicate. The green color is imparted due to the presence of chromium and traces of iron darker this color.
Typical inclusions: Emeralds are characterized by inclusions such as liquid filled cavities, liquid filled cavities with gas bubbles (2-phase), liquid-filled cavities with gas bubbles and solid crystals (3-phase), solid inclusions such pyrite and calcite, surface reaching fissures and fissures often containing oil or resin, cloudy patches with liquid fingerprint inclusions. To the gemologist inclusions are regarded as flaws, but are evidence to the authenticity, or otherwise, of the stone. They also lend a unique exotic appeal to the stone, and have often been referred to as a jardin (or the emerald’s garden) by the experts.

Emerald formation and mining methods
Emerald belongs to the mineral species called beryl. Beryl in its pure form is colorless. When it acquires a green color owing to the presence of traces of chromium it is called emerald. Blue colored beryl is called aquamarine, pink color (less common) is called morganite, yellow is heliodor. Emerald (and other beryl) crystals mostly form within a hydrothermal environment when the elements, aluminum, beryllium and silica are present in the ideal amounts and combine in a chemical reaction to form crystals of beryl. When chromium is present the crystals acquire the rich green color of emerald. Beryl crystals are found within veins and embedded in the host rocks.

Mining methods
The mining methods employed for emeralds is still rather primitive. The tools commonly used are hand chisels, sickles, sticks and hammers to procure the stone from the host rock. Explosives are only used when absolutely necessary due to the very real danger such a practice might have on any fine (and valuable) crystals.

Two main mining methods are employed:
- Shaft mining / tunnel mining: Shafts and / or tunnels are dug in the ground and the gems procured.
- Terrace mining: Emerald bearing veins are exposed by digging horizontal terraces in step-like formation along gullies. The surrounding debris is washed away with water released from a lake like reservoir above the cuttings. The emeralds thus procured are washed and sorted into parcels.

Emerald (continued)