we know that diamonds did not form from coal because
Diamond A common misconception is that diamonds are formed from highly compressed coal. Coal is formed from buried prehistoric plants, and most diamonds that have been dated are far older than the first land plants. It is possible that diamonds can form from coal in subduction zones, but diamonds formed in this way are rare, and the carbon source is more likely carbonate rocks and organic carbon in sediments, rather than coal.[17][18]
History of coal mining The Industrial Revolution, which began in Britain in the 18th century, and later spread to continental Europe, North America, and Japan, was based on the availability of coal to power steam engines. International trade expanded exponentially when coal-fed steam engines were built for the railways and steamships during the Victorian era. Coal was cheaper and much more efficient than wood fuel in most steam engines. As central and Northern England contains an abundance of coal, many mines were situated in these areas as well as the South Wales coalfield and Scotland. The small-scale techniques were unsuited to the increasing demand, with extraction moving away from surface extraction to deep shaft mining as the Industrial Revolution progressed.[14]