Learn About Natural Gemstones

Colored Stones in Red, Green and Blue

What Makes a Gemstone?

Generally speaking, a gemstone is a stone that is beautiful, rare, and durable – resistant to abrasion, fracturing and chemical reactions. Similar to diamonds, all Rubies, Sapphires and Emeralds are valued for their cut, clarity, carat weight and color. Color is a somewhat subjective factor based on your personal preference, however the market assigns a higher price to gemstones that have more intense colors that are pure and clear.


Emerald is the green variety of the mineral beryl. The precious green color is caused by small amounts of chromium within the crystal structure. Unlike other beryls, Emeralds often contain inclusions and other flaws. These flaws are not looked on as negative aspects for emeralds like they would be for other gemstones. These flaws are considered part of the character of the stone and are used to assure the purchaser of a natural stone.

Emeralds are delicate and softer than many other gems — they require special care when being cleaned and they are particularly sensitive to dramatic changes in temperature. Never clean emeralds with steam or ultrasonic processes, simply wipe with a soft cloth.

Variety Information:
Uses: Gemstone
Birthstone for: May
Color: Various shades of green
Index of Refraction: 1.57 - 1.60
Hardness: 7.5 - 8

Sapphires and Rubies

Sapphires are more readily available than emeralds. It is common practice for a broker to heat treat sapphires to improve their color and clarity. Sapphires consist of the non-red variety of corundum, the second hardest natural mineral known to mankind. The red variety of corundum is Ruby. Sapphires are well known among the general public as being blue, but it can be nearly any color.

Variety Information:
Uses: Gemstone
Birthstone for: September 
Color: Various shades of blue
Index of Refraction: 1.76 - 1.78
Hardness: 9