What is Emerald?
Emeralds are one of the world's most popular gemstones. This precious green jewel comes from the beryl mineral family. Natural emeralds are rarer than diamonds which in turn makes them quite expensive.
Colombian emeralds are considered the most expensive. This is due to their colour which comes from the presence of chromium. Brazilian emeralds' colour comes from trace amounts of vanadium.This colour is noted to have blue-brown hues but they can sometimes match the pure green hue of Colombian emeralds. Zambian emeralds generally have a blue tint. This colour is due to the presence of iron. In saying this, emeralds from anywhere can get their colour from many different elements.
Natural vs Lab-Grown Emeralds
While a lab-grown emerald is a real emerald it is not a natural emerald. Chemically, optically and physically they are the same as the natural emeralds found in the earth. Natural emeralds are formed within the earth and then mined. In the 1950’s it was discovered that emeralds could be grown in a laboratory. Lab-grown emeralds have the same chemical composition as natural emeralds, the difference is how they are formed.
Natural emeralds are formed when beryllium bubbles up from the earth's crust in hydrothermal veins. Emeralds' stunning colour variations come from coming into contact with chromium, vanadium, and iron during this process. Natural emeralds usually contain more flaws and inclusions when compared to other gemstones and coloured stones. This is because of minerals found within emeralds. The flaws or irregular patterns are not considered a bad thing when buying an emerald; they add to the uniqueness of the stone. Natural emeralds are found in countries like Brazil, Columbia and Zambia. They have many colour variations usually associated with the country where they are found.
So how are lab-grown emeralds grown?
Lab-grown emeralds are grown in a lab under similar conditions to how the natural stone forms. A beryl seed is placed in a sealed and pressurised container with pure filtered water. Also added to the container is a mix of crushed emerald and compounds like vanadium and chromium. An electrical charge is passed through the vessel and is then heated to temperatures of approximately 1800°. The molecules are then attracted to the original beryl seed and reform to create a larger emerald stone. It can take weeks to months for a large stone to form. When compared to natural emeralds lab-grown emeralds have fewer flaws or inclusions and can differ in colour variation.
There are 3 types of gemstones; Type I, Type II and Type III.
Type I gemstones typically have few or no inclusions. Aquamarines and topaz are Type I stones.
Type II is the most common type of gemstone, these will have some inclusions. Ruby and sapphires fall into this category.
Type III will show inclusions, this is the emeralds category. Many emeralds are oiled to help their clarity.
A french term for these inclusions is ‘jardin’ meaning garden as they can resemble green foliage and also they come from mother nature. Each stone's jardin is unique and can be used to identify certain stones. The cause of these inclusions comes from the forming of the stone and the mixing of different elements.
Crystals can be seen inside the emerald. A ‘halo’ may surround the crystal, this is caused by different melting temperatures of the two different materials.
Liquid inclusions are very common in emeralds. They form in cavities within the emerald. A two phase inclusion is when a gas bubble also occurs in the cavity. Three phase inclusions are very common in emeralds; these are made up of gas, liquid and crystal in a cavity.
Fingerprints occur in emeralds and are usually heavier than those seen in rubies or sapphires. They look like fingerprint patterns or wispy veils.
Needles are long thin crystals within the stone. Hollow growth tubes can also occur.
Fractures are very common in emeralds. There are two theories as to why these occur so much in emeralds, one is they are a natural occurrence from the crystal formation. The other is that harsh mining techniques cause these fractures.