The name diamond is derived from the ancient Greek word for unbreakable. Diamonds are thought to have been first recognized and mined in India, where significant alluvial deposits of the stone could be found many centuries ago along the rivers Penner, Krishna and Godavari.
The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques.
The dispersion of white light into spectral colours is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds: these are Carat (its weight), Cut ( proportions, symmetry and polish), colour (how close to white or colorless), and Clarity.