Quick Reference Guide:
All four cardinal gems share two traits:
1. They are translucent
2. They have a very high score on the Moh’s scale of mineral hardness
The value of a particular gem is usually determined by evaluating its: color, cut, clarity, and carat weight (otherwise known as the “4 C’s).” The color category (which is comprised of hue, saturation, and tone) is a very important factor when determining the value of rubies, sapphires, and emeralds. When evaluating the color of a diamond, the highest rating is given to those that are completely colorless.
Rubies and Sapphires are both varieties of the mineral corundum, or aluminum oxide.
A ruby is essentially a red sapphire, its red color is a product of adding chromium. The deeper the red is, the rarer and more expensive the gem. The sapphire’s variety of colors have to do with the level of iron or titanium in the mineral. The most well-known color of sapphire is deep blue; however, other colors include yellow, pink, and orange. The pink and orange sapphire is called a Padparadscha.
Emeralds are a variety of the mineral beryl. They score slightly lower on the Moh’s scale of mineral hardness than the other three stones, but they are still very strong. Much like the ruby, the Emerald’s gorgeous green color comes from chromium as well.
Diamonds are a colorless variety of the mineral carbon. They score the highest of all minerals on the Mohs scale. The diamond’s name derives from the ancient Greek word for “unbreakable.”