Colombia Since then, Colombia has been a leading supplier of the highest quality and greatest number of emerald supply in the world. Emerald is a medium to deep green to blue-green gemstone. The color is caused by chromium, vanadium, or a mixture of the two impurities. Colombian raw emeralds are renowned for their exceptional quality. They are usually light to medium in weight, with very fine to medium granulation and a high degree of hardness. The main current sources are the provinces of Antioquia, Bolívar, Cundinamarca, Nariño, and Valle del Cauca.
Emeralds are classified according to their chemical composition as alkaline or acid types. Alkaline emeralds contain large amounts of potassium and calcium while acid emeralds contain large amounts of sulfur. Sulfur tends to cause emeralds to discolor when exposed to air or heat so most emeralds are treated with oil before they are sold. This process also has the effect of improving the price that dealers are willing to pay for them. There are some rare emeralds that are not treated with oil; these are called nugget emeralds because of their resemblance to gold nuggets. These emeralds can sell for much more than ordinary ones.
The name "emerald" comes from the Greek word emodius which means "godly" or "divine".
Rough emeralds from Colombia Colombian raw emeralds are renowned for their exceptional quality. The hue of these emeralds is warmer and more brilliant pure green. Because deep green emeralds are a rare natural occurrence, they are highly valued and sought for. Deep green color comes from chromium oxide in the stone. Sometimes other elements are also present including iron, manganese, and silicon.
The quality of an emerald is primarily judged by how much iron it contains. The higher the percentage of iron, the harder the stone will be. Most raw emeralds that reach the market have percentages of iron between 1% and 10%. However, stones with higher percentages can be found. In general, Colombian emeralds contain about 7% iron. Stones with higher percentages can reach up to 20% or even more.
There are two main types of emeralds: fresh and aged. Fresh emeralds are those that have never been heated above 150°C (300°F). They are always white or slightly yellowish in color. Because fresh emeralds are very soft, they must be cut from its source material (a gem mine) and polished before use. As they age, fresh emeralds turn brown due to the presence of copper ions. This type of emerald is called "aged" or "used". Aged emeralds are more valuable than fresh ones because they have greater beauty density.
Colors range from vibrant, luscious green to bluish green. Raw emeralds that have not been treated or processed in any way other than cleaning are called "natural" or "uncut." These are the most valuable of all emeralds.
Emeralds are formed when volcanic ash falls into shallow groundwater containing high concentrations of potassium and bicarbonate ions. As the water evaporates, it leaves solid crystals of carbon dioxide trapped within the volcanic glass. When sunlight hits an emerald's surface, it reflects that light back out into space. This is why emeralds are famous for their bright color. They are also transparent, but mostly because there is so much air inside the stone that only 1% of its volume is mineralogically active material.
Like all gemstones, emeralds are made up of various elements: silicon, oxygen, iron, magnesium, calcium, aluminum, sodium, potassium, phosphorus, sulfur, zinc, copper, manganese, nickel, and hydrogen. Some stones are predominantly one element while others contain several elements in equal proportions. For example, a diamond is 100% carbon, while a ruby is over 80% carbon with significant amounts of iron, silicon, and oxygen.
Colombia provides almost 90% of the world's emeralds, mostly from the Muzo, Chivor, and Coscuez mines. Chivor emeralds are distinguished by their more blue tones, which are regarded higher-quality, while Coscuez emeralds exhibit a variety of features. Both types of stone can be found within the same rock mass.
The Colombian government promotes its territory as a responsible source for high quality stones that require special treatments before they can be used in jewelry. The industry has been criticized for failing to enforce labor standards or protect environmental resources. However, there is evidence that shows that many small farms have become sustainable when dealing with limited quantities of gemstones.
In addition to Colombia, some other countries provide emeralds: Argentina, Australia, Canada (both Canadian provinces), Chile, India, Indonesia, Israel, Japan, Malaysia, Mexico, New Zealand, Russia, South Africa, Sri Lanka, Switzerland, Tanzania, Thailand, and Venezuela.
Emeralds were first discovered in Colombia in 1778. Since then, over 10 million pounds (4.5 million kg) of them have been extracted from the country. At one time, it was estimated that Colombia would produce 80% of the world's emeralds. But due to poor mining practices, this figure has decreased over time.
Currently, only about 0.5% of all mined rocks are classified as emeralds.