Gem Mythbuster: Diamonds are the Rarest Gemstones

It's time for another gem mythbuster!  Today's myth:  Diamonds are the rarest gemstones.

Here are the facts:

• The process of extracting diamonds is quite laborious.  Mines move many tons of dirt per carat of diamond.  Between 200 and 250 tons of earth must be sifted through to find 1 carat of diamonds and gem-quality diamonds are relatively few.

• 80% of the world's diamonds are not suitable for jewelry.  The vast majority of the diamonds that are mined are only good for industrial use, such as diamond drill bits.

• The average size diamond that comes out of the ground is .10 carats in the rough.  For every million diamonds that are mined, only one will be found that is a quality one carat diamond.  In order to find a two carat diamond, about five million diamonds must be mined.  So, larger diamonds are more rare which is why they have correspondingly higher value. 

• Every year, approximately 130,000,000 carats (57,320 pounds) of diamonds are mined, with a total value of nearly $9 billion. 

• There are diamonds in outer space, too!  In 2004, astronomers discovered a diamond star that is 10 billion trillion trillion carats!  It's the compressed heart of an old star that was once bright like our Sun but has since faded and shrunk.  Astronomers named the star "Lucy" after the Beatles song, Lucy in the Sky with Diamonds.  According to scientists, our own sun will eventually turn into a large diamond star!

• While diamonds aren't the rarest gemstones, gem quality diamonds are rare and the larger the carat weight the rarer they are.

So, what gemstones are rarer than diamonds?  Here are a few:

Alexandrite - This rare gemstone is named after the Russian tsar Alexander II.  The first crystals were discovered in 1834 in the emerald mines in the Ural Mountains. Alexandrite is an incredible gemstone, owing to the fact that it can actually undergo dramatic shifts in color depending on what kind of light it's in.  Both of the above gems are alexandrite:  the top one shows how the gem appears in daylight; the bottom illustrates the gem in incandescent light.  It's color-changing properties (and its scarcity relative to diamond) is due to an exceedingly rare combination of minerals that includes titanium, iron and chromium.

Tanzanite - Like alexandrite, tanzanite exhibits dramatic color shifts from blue to purple that are dependent upon both crystal orientation and lighting conditions.  These color variations are largely due to the presence of vanadium ions.  It is found almost exclusively in the foothills of Mount Kilimanjaro in very limited quantities.

Black Opal - Among the different types of opals, black opals are the rarest, and are highly valued. They are mined in the Lightning Ridge area of New South Wales in South Australia and in the states of Idaho and Nevada.  Black opals are solid black or dark gray, and absorb scattered white light to produce a brilliant display of colors.

Jeremejevite - First discovered in Siberia at the end of the 19th century, gem-quality crystals of jeremejevite have since been recovered in limited supplies in Namibia.

Musgravite - This mineral was first discovered in 1967 at the Musgrave Range in South Australia, but has shown up in limited quantities in Greenland, Madagascar, and Antarctica.

Painite - First discovered in Myanmar in the 1950's, for decades there were only two known crystals of the hexagonal mineral on Earth.  Although more have been discovered, painite is still one of the rarest gemstones.

Red Diamond - O.k, so red diamonds are diamonds.  But diamonds come in a range of colors, all of which are rarer than white diamonds.  Red diamonds are the rarest  - less than 50 are known to exist - and also tend to be the smallest.  The largest red diamond on Earth — The Moussaieff Red, pictured here — weighs just 5.11 carats. The largest traditional diamonds weigh in at well over 500 carats.