For almost all of history, emeralds have been cherished and loved by man (and woman!). It is thought that the ancient Egyptians were mining emeralds as long ago as 3500-3000BC. The ancient Romans were thought to have an emerald mine in the Alps, but if they did, it was a very minor source. Indeed, until the Spanish Conquistadors discovered the abundant supplies of emeralds in South America in the 16th century, most emeralds came from Egypt.
Where emeralds come from
Today, most emeralds come from South America (Columbia and Brazil) or Africa (Zambia and Zimbabwe), although there are other smaller deposits in Asia. Historically, Columbia is the most important source, and most of the finest emeralds in the world are Columbian. In the kunsthistorisches museum in Vienna is a most amazing example, a 2860 carat emerald, where two crystals grew into each other.
What to look for in an emerald
Most people are in general agreement that the biggest thing to look for in an emerald is colour- one wants to see a rich, vibrant green, not too dark, and not too pale. All other things being equal, it is a combination of the hue, tone and saturation of colour which determines the value of an emerald. This colour is caused by a combination of trace amounts of chromium, vanadium and iron; generally, the more chromium or vanadium, the more intense the green colour. Iron gives a slightly blue tinge to the colour.
Emeralds are slightly pleochroic, that is that they exhibit two distinct colours at the same time (in this case, two different shades of green); this can be seen through a special lab instrument called a dichroscope. In day to day life, this has implications for cutting, because the pleochroism can be enhanced or reduced by the direction in which the gem is cut; it is desirable to deep the colour, so generally the stone will be cut perpendicular to the length of the crystal.
Most emeralds contain inclusions, a fingerprint from when they were created; it is so common that there is a special name for inclusions in an emerald, “jardin”. In itself, this is not a problem, so long as the stability and durability of the stone is not compromised. This is where the trained eye and judgement of a professional is invaluable. Inclusions in an emerald also help us to determine the origin of a stone; in many cases, inclusions are location-specific, so spotting one can tell us where the stone was mined.
Variations in Emerald colour
Below are some different emerald rings; in the photos you can see some of the many different shades of green in which we can find emeralds.
Almost all emeralds have inclusions; these can be helpful to identify natural from synthetic stones, and can also sometimes give a clue as to the origin of the emerald.