However gem quality diamonds are fashioned from the original crystal shape they possess a combination of brightness, sparkle, fire, and sense of purity not matched by other gems. – Jeff Scovil, courtesy Barker & Co.
Diamond’s characteristic chemical composition and crystal structure make it a unique member of the mineral kingdom.
Diamond is the only gem made of a single element: It is typically about 99.95 percent carbon. The other 0.05 percent can include one or more trace elements, which are atoms that aren’t part of the diamond’s essential chemistry. Some trace elements can influence its color or crystal shape.
Whether fashioned or rough, and no matter what their shape, all diamonds have the same chemical composition and internal crystal structure.
The way a mineral forms helps determine its identity. Diamond forms under high temperature and pressure conditions that exist only within a specific depth range (about 100 miles) beneath the earth’s surface. Diamond’s crystal structure is isometric, which means the carbon atoms are bonded in essentially the same way in all directions. Another mineral, graphite, also contains only carbon, but its formation process and crystal structure are very different. The result is that graphite is so soft that you can write with it, while diamond is so hard that you can only scratch it with another diamond.
The most common shape for rough gem quality diamond is the octahedron, which looks like two pyramids back to back. Crystals that are almost perfect in shape and transparency are called glassies.
Without any one of these factors, diamond might be just another mineral. Fortunately, though, this special combination of chemical composition, crystal structure, and formation process gives diamonds the qualities that make them extraordinary.
This diamond is a D color grade and has exceptional chemical purity. – Courtesy Lazare Kaplan Diamonds
On almost all modern birthstone lists, diamond is recognized today as the birthstone for April. Diamond is also the gem that marks the 60th and 75th wedding anniversaries.
Diamond’s unique optical and physical properties give it the highest possible luster of any transparent gemstone. This is called adamantine luster after the Greek word Adamas meaning diamond-like. – Courtesy Chow Tai Fook Jewellery Co.