Ruby is red corundum—but identifying and interpreting it requires far more than colour. Explore chromium, fluorescence, inclusions, geology, heat treatment, synthetic ruby, fracture filling and modern geographic-origin determination.
Why is ruby red, sapphire blue, emerald green and amethyst purple? Explore the atomic and optical science behind gemstone color, including trace elements, charge transfer, colour centres, crystal defects, diffraction and interference.
Inside natural sapphire lies a microscopic record of crystal growth and geological history. Learn how gemmologists interpret rutile silk, zircon, healed fissures, negative crystals, mineral inclusions and growth structures—and why sapphire inclusions can provide powerful evidence without automatically proving treatment or geographic origin.
Why is sapphire blue when pure corundum is colourless? Explore the trace elements, electron-transfer mechanisms, crystal defects and optical absorption processes that create blue, yellow, pink, purple, green and other sapphire colours—and learn why sapphire colour is more complex than a simple list of impurities.
Sapphire Heat treatment can transform colour and clarity without changing its identity as natural corundum. Discover what happens inside sapphire during heating, why low-temperature treatment can be difficult to detect, and how professional gemmological laboratories combine microscopy, fluorescence, FTIR and other analytical evidence to distinguish heated from unheated stones
Explore the gemology of natural sapphire, from corundum’s crystal structure and diagnostic properties to colour, inclusions, treatments and the scientific methods used to identify natural sapphire.
