Diamonds are still a girl's best friend, right? We love the
shiny gems. They are the most popular rocks sold today. But
what exactly are they, anyway? Where do they come from? What
else are they used for?
Diamonds are a mineral in one of the two crystalline forms
of the element carbon. They are the hardest natural
substance man knows. Diamonds are sold as gems, and used
in industrial applications for smoothing, cutting, and
polishing hard materials.
Diamonds are most famous for crystallizing in the common
colorless form. They may also be tranlucent to transparent
white, yellow, green, blue, or brown. Diamonds have a high
refractive index which is why they are so brilliant and
sparkly after cutting. The familiar shape of the diamond is
the octahedron.
The most brilliant diamonds become gemstones for jewelry and
other uses. For those that don't make it to gems, there
are other options. There is bort, which is a more poorly
crystallized or undesirable color and in fragmentary
condition, and carbonados which is gray to black opaque.
Bort and carbonados are used as abrasives for the cutting of
diamonds and the cutting heads of industrial rock drills.
Diamonds are found in alluvial formations and in volcanic
pipes, filled for most of their length with blue ground or
kimberlite, and igneous rock consisting primarily of
serpentine. Diamond yielding earth is mined by both the
open-pit method and by underground mining. After removal to
the surface, the soil is crushed and concentrated. Passing
the concentrated material in a stream of water over greased
tables does the needed sorting. The diamond is largely water
repellent and sticks to the grease and the other minerals
retain a film of water, which prevents the sticking to
the grease. Then the diamonds are removed from the grease,
cleaned, and graded for sale and use.
The earliest sources of gem diamonds were India and Borneo.
Some famous diamonds are the Great Mogul, Regent, and Pitt.
Other famous diamonds include the Hope (blue), Dresden
(green) and Tiffany (yellow). In the early 18th century,
deposits similar to those in India were found in Brazil,
mainly of carbonados. In 1867 a stone found in South Africa
was recognized as a diamond. Within a few years began a wild
search for diamonds. In 1870-1871, dry diggings including
most of the celebrated mines were discovered.
Synthetic diamonds were successfully produced in 1955; a
number of small crystals were produced when pure
graphite mixed with a catalyst was subjected to pressure of
about 1 million lb per sq in. and temperature of the order
of 5,000-F (3,000-C). Synthetic diamonds now are extensively
used for industry, mainly due to the ease of obtaining and
lower cost for them. Diamonds are still very popular and
symbolize many things. Their popularity does not seem to be
dwindling any time in the near future.
About the Author
Charmaine Stought is founder of All About Diamonds an excellent resource site dedicated to information about diamonds