Jewel Spotlight: Diamond Formation

Jewel Spotlight: Diamond Formation 

Diamonds have long been regarded as one of the most precious and highly valued stones in our culture. From earrings to necklaces, rings and other jewelry and items, they add an unmistakable element of sparkle. But how exactly do diamonds end up looking the way they do in stores? They certainly don’t start out that beautiful and shiny. In fact, it’s a process that spans several millions of years! Now there’s something to remember the next time you hold a diamond in your hands.

Diamonds actually start out as lumps of carbon deep within the earth’s crust. Over an extremely long period of time the atoms tend to crystallize due to the searing heat and constant compression. Later, the crystallized lumps are pushed up towards the surface through fissures caused by volcanoes. The resulting crystallized carbon is an incredibly hard material. In fact, the Greek name for diamond translates to “invincible”.

  • The Process of Diamond Formation – Follow the step-by-step process of where carbon comes from and how it gradually succumbs to high pressures to become a diamond.
  • The Age of Diamonds – Determining the age of a diamond can be tricky but there are a few things to look for that can give us a clue as to the diamond’s real age.

There are two main places where diamonds can generally be located. The first is through vertical pathways or pipes formed by volcanoes. When magma is pushed up through these channels, it often leaves deposits of blue-hued rocks called kimberlite rocks along the sides and surface. Kimberlite rocks often contain diamonds and are highly sought after. Later, when parts of the kimberlite deposits are swept further away by water, they end up in stream beds. These deposits are referred to as placer deposits.

  • Kimberlite – Watch an animated schematic diagram of volcanic activity and how it forms diamonds.
  • Placer Deposits (PPT) – Finding and retrieving placer deposits requires several techniques and processes of exploration and mining.

A true diamond is generally classified as a clear precious stone that was originally formed from carbon through a highly pressurized environment over several million years. There are a variety of colors that are accepted in diamonds, ranging from cool colors such as white or clear or a faint yellow or blue tinge, to warmer shades such as pink, red and even black. These colorations are caused by foreign matter in the stone. Completely clear diamonds are considered the purest types.

  • Characteristics of a Diamond – Gemstones are closely studied for their various tell-tale traits to ensure that they are indeed legitimate diamonds.
  • Diamond Coloration – The coloration of a diamond can be attributed to several causes and jewelers use a very precise scale of grading the colors.

Diamonds can be cut into many different forms but there are two that are most popular, called the regular octahedron, which is made up of eight equal-sided triangles, and the rhombic dodecahedron, made of twelve rhombus-shaped faces. Each side of the diamond is usually somewhat curved. Another common type of diamond form is the six-faced octahedron, which is almost round to some degree.

Most cut diamonds usually have entirely smooth faces, although some may intentionally have impressions cut into the stone. In their uncut state, a diamond can appear rough, unpolished and not even shiny. It is only when they are cut and polished that they truly shine.

  • Clarity Grading – The clarity of a diamond greatly affects its appearance as well as its price.
  • Diamond Clarity – Learn how jewelers evaluate flaws and imperfections in diamond surfaces.

Diamonds are sometimes formed from crystal structures that are flawed or irregular. These are called bort, or more colloquially, black diamonds, due to their coloration. Since bort is harder than other diamonds, it is often used for industrial purposes.

  • Bort – Bort can extend to stones beyond just diamonds and while they are not as perfect as pure diamonds, they are still in high demand.
  • Properties of Bort – Learn how to tell the difference between bort and other diamonds.

When people discuss the cleavage of a diamond, they are referring to the way it naturally cuts along certain crystalline layers. In an octahedron, a diamond can show unflawed cleavage.

  • Diamond Cut and Cleavage – View several 3-D diagrams and animations to understand the structure of a diamond crystal and where its cleavage lies.
  • Diamond Structure – The structure of a diamond affects its strength and how easily breakable it is.

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