Of all the gemstones known to humankind, ruby is undoubtedly the most fiery. It is neither the most abundant nor endowed with the cool brilliance of diamond, yet with its intensely rich, flame-like red color and vibrant fluorescence, it has become a symbol of life, passion, love, and power. Ruby is, in fact, red corundum. Over the course of long and complex geological processes, trace amounts of chromium enter the crystal structure of corundum and replace some of its aluminum, causing the originally colorless mineral to display varying shades of red. From ancient India, where ruby was revered as the “King of Gemstones,” to the royal houses of Europe and Asia, where it was set into crowns, scepters, and jewels, and onward to modern international auctions, where exceptional rubies have achieved prices exceeding one million dollars per carat, the history of ruby has always been intimately intertwined with human civilization, royalty, wealth, love, and desire. Yet the world of ruby is not solely one of nobility, splendor, and vows of devotion. The hardships of mining in the mist and mud of ancient deposits, together with the wars, plunder, and human greed that have accompanied these gems throughout their journeys, reveal another, little-known side of this brilliant red. Ruby, therefore, is not merely a precious gemstone, but also a mirror. It reflects humanity’s pursuit of ultimate beauty, its longing for supreme power, and its yearning for passionate love. It also reflects the conflicts and choices between science and experience, nature and human creation, intrinsic value and market desire. From multiple perspectives, this series will explore ruby’s geological formation, mineralogical properties, quality evaluation, principal sources, and inner world beneath the microscope; help readers understand the treatment comments and specialized terminology found in reports issued by internationally respected gemological laboratories; recount the legendary stories of celebrated rubies throughout history; and uncover the true identities of historic jewels long believed to be rubies, but which were actually red spinels. Through this series, readers will not only appreciate ruby’s neon-like, radiant red glow, but also gain a genuine understanding of the science, history, culture, and humanity it carries within.