Short answers, pulled from the story.
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. It is composed entirely of carbon atoms and is insoluble in water. The material is a poor conductor of electricity and possesses the highest hardness and thermal conductivity of any natural material.
Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits could be found along the rivers Penner, Krishna, and Godavari. Diamonds have been known in India for at least 3,000 years but most likely 6,000 years. They were treasured as gemstones since their use as religious icons in ancient India.
Most natural diamonds have ages between 1 billion and 3.5 billion years. They were formed at depths between 150 and 250 kilometers in the Earth's mantle, although a few have come from as deep as 800 kilometers. They were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites.
Colors in diamond originate from lattice defects and impurities such as nitrogen, boron, and hydrogen. Nitrogen is responsible for the yellow and brown color in diamonds, while boron is responsible for the blue color. Irradiation and plastic deformation of the diamond crystal lattice also cause colors such as green, brown, pink, and red.
The United Nations, the diamond industry and diamond-trading nations introduced the Kimberley Process in 2002. The Kimberley Process aims to ensure that conflict diamonds do not become intermixed with diamonds not controlled by rebel groups. According to the International Diamond Manufacturers Association, conflict diamonds constitute 2 to 3% of all diamonds traded.
Antwerp is the de facto world diamond capital where 80% of all rough diamonds, 50% of all cut diamonds and more than 50% of all rough, cut and industrial diamonds combined are handled. The city also hosts the Antwerpsche Diamantkring, created in 1929 to become the first and biggest diamond bourse dedicated to rough diamonds. New York City is another important center where almost 80% of the world's diamonds are sold.