Congratulations! You have found a Green Diamond! The word Diamond comes from the Greek adamas, meaning "unbreakable", "proper", or "untamed".
A chemically pure and perfectly structured diamond is transparent with no hue or color. The colors occur from chemical impurities and/or structural defects. However, depending on the hue and intensity of the color, these defects can add to the diamond's value. Intense blue and pink diamonds are significantly more valuable, for example.
Diamonds can be found in a variety of colors including yellow, pink, green, red, blue, brown, and black. "Fancy color" diamonds are valued on a different scale than colorless diamonds.
Diamonds have been treasured as gemstones since their use as religious icons in Ancient India. Diamonds are the hardest known natural material on the Mohs scale with a hardness of 10. Famous blue diamonds include the Hope Diamond, the Blue Heart Diamond, and the Tereschenko Diamond.