Rubies and sapphires are derived from the mineral corundum. Corundum is hard and heavy and is rated a 9 on the scale of hardness. Diamonds are the hardest stones and are rated as a 10. Rubies and sapphires are the most prized among the corundum stones which has a very wide variance. 

Corundum can be found in colors such as purples, yellows, pinks, reds and blues. Red corundum is classified as a ruby while the blues are sapphires and any other color variance is titled by its color followed by the labeling sapphire. This also includes the green sapphires. 

 

The main difference between rubies and the other color varieties is the presence of mineral called chromium. Rubies that are red have significant amount of the mineral chromium while a minute amount of chromium creates a pink stone, Color variance occurs when other minerals enter into the mix with corundum. The strength of the other compounds along with the environment makes for different colors in the same primary element. 

 

The introduction of the element titanium to corundum produces the blue stones which are classified as sapphires. The internal features of the stone also help to determine coloration. Corundum is formed in rocks known as schist or igneous rocks. They are however hardly mined from the rocks but are typically mined from streams and river beds. Corundum is mostly found in gray, white, and brown. Yellow, pinks, pale blue and green are some of the color varieties. 

 

 

Rubies and sapphires are mined in different parts of the world. The most desired red rubies are mined in Burma and are called Burmese red. Thai rubies are often not as red as the Burmese and appear to have a blue undertone. Undertones are also noticeable in Tanzanian rubies with some stones having brown and sometimes orange undertones. Kenya, Cambodia and areas of China, NY, Australia, Madagascar, Canada and South Africa also mine corundum. 

As with rubies, the most sought after blue sapphires are the Burmese red and the Kashmir are the most desired sapphires. Sapphires from Sri Lanka are of a lighter shade blue but are also highly prized. Montana sapphires are mined in the United States of America and are desired for their unique coloring. Blue sapphires are found in Africa, Australia, Brazil and Afghanistan. 

Rubies and Sapphires are being mined in different regions, but the Burmese stones are still considered to have the deepest reds and the deepest blues.