What is a diamond?
Carbon is the only element in diamond. Impurities such as boron and nitrogen can also be found, although they are not part of the chemical structure. The unique properties of diamonds are a result of its crystal structure. Diamond is the hardest material known to man and is also the least compressible with stiffness like no other.
How are natural diamonds formed?
Contrary to popular belief, diamonds are not formed by compressed trees and vegetation, such as coal. The core processes of forming diamonds involve extremely high temperatures and massive amounts of pressure. These conditions can be achieved deep under the Earth’s surface, around 100 to 120 miles below. Temperatures at this depth can reach as high as 1300 degrees Celsius. Combined with pressure, the carbon atoms crystallise in a cubic arrangement thus creating diamonds. From deep inside the Earth, the diamonds are forced upwards using magma flow as a transporter.
The age of a diamond
It may come as a surprise that the youngest diamonds on earth are around 1.2 billion years old, the oldest being 3.3 billion years old, close to the birth of planet Earth. Scientists studying in South Africa believe that there have only been two or three occasions in the Earth’s history when diamonds have been made, all of which happened billions of years ago.
Fancy colored diamonds are around ten thousand times rarer than colorless diamonds. The natural processes used to create colorful diamonds happen very rarely. Natural radiation and pressure can result in a diamond acquiring a specific color, although more commonly, a diamond obtains color through the intervention of another element during its creation. Examples of these color-giving elements are boron and nitrogen.
Where and how are diamonds mined?
Diamonds are mined in countries all over the world: Angola, Botswana, South Africa, Congo, Zimbabwe and Tanzania are just some of the countries in Africa with large diamond mines. Russia and India also have accredited diamond mines. Other countries mining diamonds include the USA, Canada and Australia.
There are several methods used to effectively mine diamonds. Methods vary depending on the distribution of the diamonds and the lay of the land. Open-pit diamond mines are used when tunnelling is not an option. The diamonds are amongst gravel, sand and other loose material near to the surface.
Placer mining is used to extract diamonds from alluvial, eluvial (residual deposits of soil) and colluvial (loose rock) deposits, achieved mechanically and hydraulically with the use of machines. Sifting by hand is another process used in placer mines. Hard rock mining is the process used in the excavation of minerals containing metals, and the same process is adopted for mining diamonds and gemstones. This method uses deep underground tunnels to reach the diamonds.
The brilliance of a diamond is dependent on the cut. Quality diamonds must be professionally cut, and not 'spread'. 'Spreading' is an improper practice which compromises the proper proportions of the diamond to make it increase in weight. A classic round, brilliant cut diamond has 58 facets – 33 on the top, 24 on the bottom, and the culet which is 1 point at the bottom. Every one of these facets has to be placed in exact geometric relation to the next when the stone is being cut.
The clarity of the diamond depends on the number, size and location of inclusions found in the stone. Under the magnification of a jeweler's loupe, imperfections or trace minerals can be seen in the stone. These are called 'inclusions'. The diamond will increase in value when there are fewer inclusions present, and will be clearer and more brilliant. A diamond with no inclusions is extremely rare and valuable, and is given the term 'flawless'.
When viewed under a jeweler's loupe, most diamonds contain slight traces of light brown or yellow pigment. Colorless and near colorless diamonds are much more valuable, and taking the stone's size into consideration, a single increase in color grade can raise the value of a diamond by thousands of pounds per carat. Engagement rings traditionally use diamonds that are colorless, or near colorless.
Naturally, diamonds can be found in shades of blue, green, red, pink and deep yellow. These are known as 'fancy diamonds'. Worldwide, colorless diamonds are graded using an alphabetical scale. Colorless or 'rare white' diamonds are graded D,E and F, the most valuable being the D grade, which is extremely rare.
Judging a diamond on the carat weight alone can be very misleading. The cut, clarity and color of the diamond are extremely important and have to be taken into account. A large stone will not generally be valuable if it lacks purity, high grade color and brilliance. However, as larger stones are rarer than smaller ones, the value will rise exponentially with carat weight, making a 3.0 carat diamond worth more than three 1.0 carat diamonds of equal quality. So, when making your decision as to which diamond to buy, take all these factors into account – color, clarity, carat weight and cut.
Amethyst is transparent, violet quartz which is mined in South America and Southern Africa. Amethysts are also mined in Australia; such amethysts tend to be smaller and darker in appearance. Once thought to be as rare as sapphires and rubies, amethysts became highly sought after and valuable. Since the discovery of vast quantities in Brazil, the value of amethyst dropped but its distinct beauty and unique color remained, making amethysts very desirable to jewelers and jewelry lovers alike.
Garnets are well known by their deep red, warm color often found in antique jewelry. Although this color is the most common in garnets, few people are aware that there is a spectrum of colors available. Garnets are found all over the world: Brazil, Thailand, Czech Republic, USA and Africa are just some of the countries where these stunning stones are mined. The variety of hues and plentiful supply combine to keep the garnet at the forefront of style and fashion trends.
Aquamarine stones are typically mined in Brazil, Russia, Afghanistan, India and Pakistan. The name is derived from the color aqua (meaning water) and mar (meaning sea). From light sky green-blues to deeper blues, aquamarines are usually free from inclusions and internal blemishes; a more intense color would increase its value.
Chromium and vanadium are responsible for the many intense and radiant hues emeralds have to offer. It is said that emeralds of high quality can be more valuable than diamonds, and unlike most gemstones, inclusions are tolerated. Emeralds are found all over the world: eastern Africa, India and Madagascar have been mining emeralds for hundreds of years, and of course emeralds are also found in South America.
The remote outback deserts of Australia play host to 95 per cent of the world’s opal abundance, the remainder originating from Brazil, USA, Japan, Honduras, Kenya, Czechoslovakia, Peru and Canada. Opal is a member of the quartz family and its name comes from the ancient Indian language of Sanskrit; ‘upala’ meaning precious stone.
From the French word for Lemon we get Citrine (citron). This gemstone is another member of the quartz family and is rarely found naturally. The vast majority of citrine is mined in Brazil, although most commercial citrine is heat-treated amethyst.
A sapphire can be any color of the spectrum including white and black. For most of us we think of sapphires as being blue; many shades of blue exist and this is largely due to the titanium and iron content within the stone’s molecular structure. If a sapphire is red, this is indeed a ruby. Sapphires are mined in South America, Asia and Australasia.
Peridot is one of the few gemstones which can only be found in one color, but what a beautiful color it is. Shades of green differ depending on the amount of iron within its crystal structure. This can result in pale olive greens to more intense uranium greens and everything in between. It is found in countries all over the world: USA, Myanmar, Egypt, China, Sri Lanka and Pakistan to name a few.
Pearls are created when an oyster lays down layers of nacre around a foreign object which has entered its shell. Pearls are created by chance, and in years past this gave way to pearls being used as important financial assets comparable with land and property of today. Thousands of oysters can be searched without finding a single pearl. In modern times it is possible to artificially introduce foreign objects to a pearl oyster in the hope of pearl creation. Pearls can be found all over the world but areas such as Japan, China, Tahiti, Australia, Indonesia, Philippines, USA and Burma have the best conditions for pearl production.
Blue topaz can be a popular alternative to aquamarine, and has a variety of color depths. Different names are given in the gem trade to the various depths, such as Sky Blue Topaz, London Blue Topaz, and Swiss Blue Topaz. The lightest shade is Sky Blue, the darkest being London Blue. These beautiful gemstones are found in Brazil, Sri Lanka, Russia, Australia, Africa, Mexico and Pakistan. Topaz is also found in a spectrum of other colors ranging from vivid pinks, yellows, golds, greens, reds and browns.
Tanzanite was newly discovered in 1967 near the Usambara Mountains in Tanzania. The only place on Earth known to yield tanzanite is in eastern Africa. They come in several colors with violet being the most well-known. Yellow, green, brown and blue can also be found, the crystals of which can be heat treated to enhance color.