An Overview of the Emerald

Emeralds are a type of beryl, a mineral composed of beryllium, aluminum, silicon, and oxygen. These elements are found in the continental crust, so the colorless beryls normally found are not very rare. As the earth was forming, beryllium migrated to the earth's crust while chromium moved into the earth's mantle. There is typically no reason for either of these elements to come into contact. They are members of different chemical families that separated to different parts of the earth, billions of years ago. Emeralds get their green color because some of the aluminum atoms in the beryl crystal are replaced primarily by chromium atoms. This slight difference is what makes emeralds so rare.

In Colombia, emeralds are found within layers of black shale. These sediments were deposited on the floor of a shallow inland sea about 100 million years ago. The shale contains everything that washed off the various rocks that made up the surrounding land - including most of the ingredients of emeralds. Two times in the last 100 million years, there have been surges in the continental plates that brought together all the ingredients needed to form Colombian emeralds. The Atlantic Ocean was expanding and pushed South America against the Pacific. The Andes were raised, causing the thick stack of black sediment under the shallow sea to buckle. Large sloping faults formed several miles down in the sediments and hot water was squeezed out of them, escaping upward along the faults. The superheated water moved through the faults and dissolved the emerald ingredients. Finally, it pooled under a layer of especially impermeable shale until the pressure shattered that layer. The hot solution shot up through empty cracks in the calcite veins and cooled. As it cooled, emerald crystals began to grow immediately. The emeralds grew unconstrained, without the impurities that often cloud emeralds found in other parts of the world.

Emeralds, among the rarest of gems, are always found with natural inclusions. The reason for the formation of these inclusions is a mystery that scientists have yet to solve. It is very likely that the chemistry of emeralds, composed of aluminum and beryllium, goes through a disruptive substitution of larger chromium atoms that succeed in imparting a deeper green than otherwise would be possible. There is, however, a trade-off for gaining incomparable color. The addition of very minute amounts of chromium needed for the natural "greening" of emerald causes the crystal structure to strain to accommodate the atoms of this trace element - or so it is theorized.

All emeralds that are used for jewelry go through the same six part enhancement process to become the gemstones we know. The steps are sawing, preforming, cutting, polishing, cleaning, and clarity enhancing. Virtually all emeralds require the process of clarity enhancement. This process involves immersing the emerald into a colorless or near-colorless medium. An infinitesimally small amount of the clarity enhancing medium penetrates open fissures. The volume is so small that it is usually not measurable by weight (typically as little as 1/100,000 of a gram). It should be assumed that every emerald has been processed in this manner unless it has an accompanying laboratory report indicating that there is no evidence of a clarity enhancement medium. Such extraordinarily rare gems command a considerable premium.

Agents used for clarity enhancement are: Colorless oils, prepolymers, uncatalyzed resins, paraffins, and polymers. Most Colombian Emeralds are cedar oil-treated (Colorless oils) which is a 100% natural treatment dating back to ancient times.

"Emeralds have been treasured for thousands of years. The infatuation with Emeralds dates back to ancient Egypt and Rome. It is said that Cleopatra was always adorned in Emeralds and that this was her most treasured jewelry"

Emeralds have been treasured as adornments in the form of jewelry for centuries. Emeralds are at least twenty times rarer than diamonds, but in the finest grades sell for approximately the same per-carat price as diamonds.

Widely recognized as the Birthstone for May and Astrological affiliation with Cancer (June 22 – July 22), Emerald is also the celebrated gemstone of choice for 20th, 35th and 55th Wedding Anniversary. The Emerald continues to be one of the most popular of precious gemstones.