Diamond

In the Museum

Seven diamonds from the first mine in Canada were donated to the Canadian Museum of Nature in 2000 by the mine's owners and operators: BHP Diamonds Inc., Dia Met Minerals Ltd., Chuck E. Fipke and S. Blusson.

Diamonds come in different shapes, often as regularly shaped crystals. The external geometric shape of such minerals is a manifestation of the internal atomic structure. The well-ordered atomic structure of minerals is described as crystalline and so a synonym is crystal structure. The regular external geometric shape that is produced is referred to as a crystal.

Diamond has a basic three-dimensional atomic structure that functions as a building block. It is tetrahedral, with a carbon atom marking each "corner". Different depositions of these tetrahedrons produce a variety of crystal habits (shapes). Local environmental conditions affect which habit will grow. The most common shape is an octahedron, but there are others.

Octahedron
Four of Nature's Canadian diamonds are crystals that are octahedrons. Three of these eight-sided specimens are about the same size, just over a carat each. The fourth is the largest, weighing 3.19 carats.

Macle
One of the seven diamonds formed into a macle, which is a twinned crystal. This diamond also weighs a little more than a carat.

Bort
Many diamonds are not clear, colourless, regularly shaped crystals. Often, this is because there was not enough room amid the press of surrounding matrix for a crystal shape to form. Sometimes diamonds are irregularly shaped because there are traces of other atoms mixed in, and the influence of their atoms distorts the structure that would be formed by carbon atoms alone. Impurities can affect the diamond's colour: impurities that distort the crystal structure affect the way light is absorbed, making colour apparent to the eye.

At 27.24 carats, the largest of the seven specimens is one such irregular diamond. Black diamonds like this one are called bort. Bort are unsuited for gem purposes because they are opaque. They are usually crushed into grit for grinding and polishing.

Brilliant-cut gem
The great ability of diamond to refract light is exploited by the shape of the one diamond that was polished before it reached Nature's collections. This 0.53 carat gem is polished in the brilliant cut, the most popular style of faceting for diamonds because it is the most effective at showing off diamond's special sparkle. This polished diamond is microscopically engraved with Ekati^TM, thereby marking it forever as one that came from this Canadian source.

Complementary minerals
Nature's collection is enhanced by samples of the minerals that compose the kimberlite in which the diamonds were found. They include olivine, ilmenite, garnet and chrome diopside.