What is the difference between sapphire and diamonds?

Researching this answer has been today's bit of education. Sapphires are part of the corundum group and are nearly the hardest group of stones known to man registering 9 on the Moh's scale, only diamonds which are made of carbon are harder registering 10. They can come in many colors, when red they are called rubies, all other colors are sapphires, not just the blue ones. Apart from price, the difference among these two stones is its chemical composition.

* Diamond is made of "Carbon - C" with traces of metals like iron and nickel. Graphite is another stone which is made of "Carbon

• C". The only difference is of their atomic structure. It is

interesting that at certain temperature and pressure a graphite can turn into diamond and diamond into graphite. * Sapphire is made of Aluminum Oxide, with traces of Chromium, Iron, Titanium etc. which are responsible for its colors.