Diamonds glitter through countless legends and still fire imaginations. Unlike any other commodity, diamonds are famed for their physical properties and their illustrious place in history, helped in modern times by intense marketing.
According to Ad Age, “A diamond is forever” is the No. 1 commercial slogan of the 20th Century.
Today, heirloom and coloured diamonds are fetching ultra-high prices in auctions, with wealthy collectors vying for the very best. For example, the Hancock Red, weighing only 0.95 carat, was sold by Christie’s in 1987 for $880,000 or $926,315 per carat.
Adamas from ancient Greek, meaning unconquerable or indestructible, is the root of the word “diamond.”
Depending on the geometric arrangement of carbon atoms, they can form diamond — the hardest substance known, or graphite, the softest of mineral substances.
Physical Properties
Two characteristics of diamond grant its premier position as a gemstone: hardness and optical properties. On the Mohs Comparative Scale of mineral hardness, diamond tops the list with a value of 10. Corundum, the mineral name of ruby and sapphire, has a value of nine. However, measured by the quantitative Rosival Scale, diamond is 1,000 times harder than corundum, the second-hardest substance, and about five million times harder than graphite, which has a Mohs hardness of one. Diamond’s hardness, of course, is highly valued for tools that cut, grind, polish and drill hard materials such as metals, gemstones and rocks, and for dentistry and medical applications, such as precision eye surgery and other microsurgeries.
Diamond’s colourful “fire” is due to its high index of refraction, a measure of how much a light ray is bent upon passage into and out of the stone, and its optical dispersion, a measure of the degree of angular separation of white light into its rainbow colours.
Value: The “Four Cs”
The “Four Cs” refer to the four main elements in a polished, cut gem diamond’s appraisal: carat-weight, colour, clarity and cut. The value of diamonds with the same general properties increases exponentially with weight. For example, a one-carat flawless, colourless, round, brilliant, excellently cut stone retails for $22,890 US. A two-carat stone of similar quality sells for $90,920. And an equivalent four-carat stone retails at $421,990. The term “carat” comes from the Greek “keration,” meaning locust tree.
The metric carat is 200 milligrams, which approximates the weight of locust tree seeds used by 19th-Century diamantaires (diamond producers or cutters) for weighing diamonds.
High prices for diamonds generally reflect the rarity of larger stones. De Beers stated in a 2002 report that only 400,000 stones of one carat or greater are produced annually from the world’s mines. Moreover, about 50 per cent of diamond weight is lost in cutting and often two stones are produced from one diamond. To produce a one-carat cut stone, a well-formed 2.6 carat rough octahedral crystal would be needed. That amount would also yield a 0.30-carat stone.
The average size of a rough diamond is about 0.10 carat, which would mean about 700 million individual stones comprise the 70 million carats of gem-quality diamond mined annually. According to De Beers, 92 per cent of them are cut in India, where more than a million workers do the job. Most of the diamonds cut are below 0.08 carats. The smallest, 0.005 carat, are used in pavé, the tiny sparkles seen on jewelry pieces. With 70 million carats weighing only 14 tonnes, it would take six years of production to fill a six-metre shipping container.
Individual mines generally grade from 0.3 carats to one carat per tonne of ore. The lowest is 0.08 carats when stone quality is excellent. The highest is the Argyle Mine in Australia with 6.0 carats, but having only five per cent gem quality, that material is worth, on average, only $25/carat. Even one-carat-per-tonne ore is made up of 30 to 50 mainly tiny diamonds, half of which are low-value non-gem quality.
The number of mines is also small. In 140 years, of the 7,000 kimberlite pipes (the conduits in igneous rocks that carry diamond towards the Earth’s surface) found, 1,000 have diamonds, but only 60 proved to be economically viable and 11 mines account for two thirds of global production, a fairly puny presence for such a glitzy global business.
The violent birth and hard early life of a diamond
Diamonds form under pressure at depths of 150 to 180 kilometres in the earth and at temperatures optimally around 1,300C. These unique conditions are only to be found in the Earth’s “mantle” layer, below the thick cooler regions of the Earth’s crust, in formations that are at least 2,500 million years old. In the diamond stability field at this depth, diamonds crystallized over time.
The rocks are of Precambrian Age, which can be divided into two broad categories: the Archean Eon (between 2.5 billion and four billion years ago when the crust of the Earth formed) and the Proterozoic Eon (between a half-billion and 2.5 billion years ago, when simple forms of life came into being.)
The latter is divided into two units: a younger one, between a half-billion and one billion years old, and an older one, which is one to 2.5 billion years old. As structural units, these are referred to respectively as Archons, Protons and Tectons. It is only in the Archon regions that diamond pipes can be found. These, therefore, are the target areas for exploration and the source for alluvial diamonds in streams and seabed deposits that have been transported away from their sources.
The final depositing of diamond at or near the Earth’s surface, is a remarkable event. Molten volcanic magma from deeper in the mantle, below the diamondbearing layer, rises up and incorporates diamonds from their own quiet layer and, under immense pressure, fractures and penetrates upwards through the crust. As the magma moves upward, it accelerates from 20 kilometres per hour to 1,200 kilometres per hour, reaching the surface with explosive force.
As support for such a violent birth for a diamond pipe, at 300 metres depth in the Ekati Mine in the Northwest Territories, metre-long chunks of preserved redwood trees were found buried in kimberlite ore. Clearly, the explosive eruption occurred in a redwood forest and trees within the blast and along the edge of the crater toppled in and were interred by airborne rock falling back and additional volcanic material from below in the final stages of the eruption. Of broader geologic interest, it is clear that a California climate existed around Ekati 53 million years ago. Climate evidently can change dramatically of its own accord.
Diamonds in situ occur in kimberlite, a dark green-black igneous rock dominated by iron-magnesium silicates, high carbon dioxide, high water content and exotic trace minerals. They are also geologically interesting as samples of the Earth’s sub-crustal mantle layer. The term “pipe,” in kimberlite pipe, refers to the usually circular cross-section and the fact that it represents a conduit of volcanic fluids from below the Earth’s crust. Kimberlite pipes are carrot-shaped, tapering downward.
Diamonds also occur in stream gravels, resulting from erosion of diamond pipes and are an important resource in India, Africa, Australia, Brazil, Venezuela and Guyana.
A brief history
Clashing empires, plundering hordes, freebooters, thieves, royal intrigues and romances embroider the rich history of diamonds. Diamonds have even had a place at the table — as collateral for loans — in times of war and economic hardship. For more than 3,000 years, diamonds have symbolized power, wealth and love, along with their spiritual, medicinal and supernatural powers.
The ancient Romans were the first to import diamonds in quantity. Pliny the Elder complained in a letter that trade in luxury goods with India was draining the Roman treasury. He was eminently aware of diamonds, having written of their superior hardness and magical properties in his 10-volume book of knowledge, Naturalis Historia¸ published in 77 AD. He noted the industrial use of diamond fragments as well: “These particles are held in great request by engravers, who enclose them in iron, and are enabled thereby, with the greatest facility, to cut the very hardest substances known.”
Augustus Caesar (ruled 27 to 14 BC) received two trade missions from India in 25 BC and 21 BC. Modern archeologists discovered large caches of Roman gold coins of the emperors Augustus, Tiberius and Nero. Unearthed near modern-day Pondicherry on the southeast coast of India and near Coimbatore on the southwest coast, along with pottery, beads and lamps, they marked Roman trading settlements. Chinese references of the period record iron scribes coming from Rome. Their interest in diamond was apparently only as a carving tool for jade and other materials.
The fabled large Indian diamonds came to light after the Arab invasions of India in the 8th Century, Turkish conquests in the 12th Century — the Turco-Mongol conquerors who created the 200-year Moghul Empire in India — and the latter’s crushing defeat in 1739 by Nader Shah, ruler of Persia. The surrendered Moghul treasury contained a rich trove of gems, including the Koh-i-Noor (meaning mountain of light in Persian) and Darya-i-Noor (meaning sea of light) among other substantial stones that are part of individual diamonds’ romantic history. These two diamonds today respectively preside as British and Iranian Crown jewels.
Following Roman activity around the beginning of the Common Era, it might be expected that Europe would have been a continuing and growing force in diamond trade. However, it wasn’t until Bishop Marbode’s 11th-Century book, Libellus de lapidibus preciosis, reintroduced to Europe the medicinal and other magical properties of gems that diamonds began appearing in European regalia and jewelry. The rebirth of European diamond trading began in Venice and diamond cutting is thought to have originated there after 1330. By the late 14th Century, the trade had already begun shifting to Bruges, Paris, Amsterdam and Antwerp.
In 1499, Portuguese navigator Vasco da Gama discovered the sea route to the Orient around the Cape of Good Hope, and diamonds began to flow directly from India to Lisbon and Antwerp. In 1602, the Dutch East India Company soon took over the Indian diamond trade. Coincidentally, the company also set up a colony in South Africa, and settled it with Dutch farmers (Boers) to provide fresh produce for the company’s ships on their long voyages between Europe and the Orient. Little did they know at the time that this territory would become far greater a producer of diamonds than India.
An individual, Jean Baptiste Tavernier (1605-1689), travelled on six occasions to India to purchase diamonds for Louis IV of France. His were the first objective accounts of diamond production and trade. He also gave descriptions of some famous diamonds, including those he saw among the Persian Crown jewels.
The diamond’s unique connection to India was broken in 1725 during a gold rush along the Rio Jequitinhonha in Brazil’s Minas Gerais state, where diamonds began to turn up in prospectors’ pans. This new source supplanted dwindling Indian diamond supplies for the next 140 years. Then, in 1866, near Hopetown, South Africa, the final twist in the story occurred. A farm boy, Erasmus Jacobs, found a pretty stone that turned out to be a 21.25-carat diamond, subsequently named Eureka. Alerted to the find, others began finding diamonds around the town of Kimberley. It became clear that an unparalleled supply of diamonds was about to present itself. No longer was this king of gems to remain the stuff of emperors, monarchs and the nobility.
Geologists soon began to unravel the science behind the formation of diamonds and the placement of diamond pipes, which guided the search for more. Diamonds were soon found in a dozen countries in Africa, then in Russia and Canada, among others.
What’s next?
Perhaps De Beers’ slogan “A diamond is forever” will change to “diamonds are for everyone.” Technology will be the engine for such a trend. Laser cutting has become commonplace. Manufactured diamonds were first produced for industrial usage, but in the past few decades, a small number of gem-quality diamonds of up to half a carat have been achieved as well. Industrial diamonds from such places as Ireland and the U.S. now make up 95 per cent of all diamonds.
The Canadian chapter
In the mining trade, looking for mines is called “looking for elephants in elephant country.” The search for diamond is no exception once the first elephant is found, and the first elephant is almost always found (to carry on the animal metaphor) by a determined lone wolf with an idea and a shoestring budget.
Charles Edgar Fipke, born in Edmonton in 1946, was one such person. In Canada, spectacular continental glaciers, with ice up to three kilometres thick, covered the bedrock over thousands of kilometres and destroyed any useful alluvial deposits that might have led to the discovery of diamond pipes. Fipke, however, visualized the glaciers similarly ploughing over diamond pipes and distributing diamond indicator minerals “downstream,” hundreds of kilometres from their source in the gravels and soils along the direction of ice movement. He found diamond indicator minerals in the soils near the west end of Great Slave Lake and during the following decade, he traced the minerals train 300 kilometres north, where he found the Ekati diamond pipe.
An earlier Canadian who pioneered diamond exploration and development was John Williamson, a geologist who obtained his PhD in geology at McGill University in the 1920s. He first worked with De Beers in Zambia and then purchased a declining diamond operation near Mabuki, Tanzania, in 1936. He struggled to make a living from it and to support his exploration for a new mine. In 1940, he discovered the diamond pipe at Mwadui that became the Williamson diamond mine, which he developed. It turned out to be one of the biggest kimberlites ever found. Its most famous diamond is the Williamson Pink, a 23.6-carat stone he presented to Princess Elizabeth and Prince Philip on their wedding day in 1947. Williamson died in 1958. The mine is still in production.
Today there are five operating diamond mines in Canada. Ekati, Diavik and Gahcho Kue are in the cluster containing Charles Fipke’s discovery. The Victor Diamond Mine is at Attawapiskat in the James Bay region of Ontario and the Renard project is in central Quebec. A sixth, east of Prince Albert in Saskatchewan, is under development. It is said to be one of the largest diamond pipes ever found. Two other mines — Jericho in Nunavut and Snap Lake in the Northwest Territories — are currently dormant, awaiting better diamond prices.
A small diamond-cutting and polishing industry finishes Canadian diamonds. Crossworks Manufacturing Ltd., a subsidiary of HRA-Sun Diamond Group of Companies, operates factories in Vancouver, Yellowknife and Sudbury. The company takes advantage of government agreements through which up to 10 per cent of rough diamond production by value is provided to the factory at market price. Embee Diamond, a division of Embee Diamond Technologies Inc., operates a factory in Prince Albert near the fledgling Saskatchewan diamond mine.
Not everyone embraces the development of diamond mines. The Weenusk First Nation, a Cree community on the Attawapiskat River, had mixed feelings about De Beers’ new Victor Mine in their native territory. Chief Edmond Hunter said at the time: “It is difficult, because the youth wants development for their future.” The Cree at Weenusk share many values with the Cree peoples along the James Bay coast where traditional ways of life prevail over modern development.
The Victor Mine, however, is one of the richest in the world and a big chunk of the De Beers empire and the community has benefited in many ways: De Beers has paid more than $40 million in taxes since opening the mine and pays up to $2 million a year in royalties to Attawapiskat. And 35 to 40 per cent of the mine’s labour force is aboriginal. Further, De Beers claims that every diamond at the mine is mined in a “sustainable and ethical manner.” Still, some locals say that their river and their land made them happier before De Beers came into their lives.
Yana Amis is a mineral commodity economics researcher and president of a mining consulting firm.
