Emeralds are derived from a mineral known as beryl which occurs naturally. The green coloration is due to traces of an element called chromium. In the United States, beryl that is green as a result of traces of the element vanadium may be called emerald, but this is not permitted in Europe and the UK.

Geologists have a hardness scale for minerals, and it is called the Mohs scale of hardness. On this scale, emeralds are 7.5-8, the scale going up to a maximum of 10.

Almost all emeralds have imperfections known as inclusions within them, and these may cause weakness. Inclusions cause them to be less resistant to breakage than those which are inclusion-free.

Emeralds without some form of inclusion are particularly rare, and because of this are very valuable. Tiny liquid-filled inclusions within the gemstone are known as ‘jardins’, and have the appearance of a garden.

When it comes to the value of an emerald, in common with other gemstones the 4 ‘C’s of Color, Cut, Clarity and Crystal determine its worth.

Almost all emeralds have been oil-treated to improve clarity, and in the US this information must be disclosed at the time of sale. Cedar oil or synthetic oils are used for this treatment, and care must be taken not to lose this oil during cleaning.

Emeralds are mined in many parts of the world, but possibly the place most noted for its emeralds is Colombia. It is here that a rare form of emerald known as a trapiche emerald is found. This type has a 6-point radial pattern due to carbon impurities.

Egypt, Pakistan and Austria are some other well-known places for emerald mining, but there are quite a few other countries with this type of mine.

Emeralds have been made synthetically by several different processes over the years. Typically a seed of beryl forms the base on which the emerald builds up.

When it comes to birthstones, the month of May has emerald as the birthstone. Emerald has also traditionally been the astrological stone for the signs of the zodiac Cancer and Taurus. People also give emeralds to their marriage partners on their wedding anniversaries of 20, 35 and 55 years.

Major emeralds which have been discovered include the Gachala emerald from Colombia, which weighed 172g, and the 37.82 carat Chalk Emerald also from Colombia.

It is possible to cut an emerald into any one of a number of shapes, but the most popular is the ‘emerald cut’, as it shows off the gemstone so well. Other cuts can be oval, marquise, pear or round.

Read more facts about emeralds and emerald rings at Sarah Carter’s site Emerald Rings Guide. You can also get facts on antique emerald rings. This article, About Emeralds – A Quick Guide has free reprint rights.