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.
A 10× loupe is one of gemmology’s simplest and most useful instruments—but only when used correctly. Learn how to use a 10x loupe with professional focusing technique, lighting, systematic gemstone inspection, what inclusions can reveal, and when magnification alone is not enough
For more than six millennia, lapis lazuli travelled extraordinary distances from the mountains of Afghanistan to ancient Mesopotamia, Egypt and later Europe. Discover its geology, ancient trade, cultural prestige and transformation into precious ultramarine pigment.
The history of sapphire is more complicated than its name suggests. Ancient sappheiros often described lapis lazuli, while surviving Roman and medieval jewellery confirms the later use of true corundum sapphire. Follow the evidence through ancient texts, trade, medieval lapidaries, religious symbolism and surviving museum objects.
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
Successful sapphire faceting begins long before the first facet is cut. This professional guide explains how to assess natural sapphire rough for colour, crystal orientation, pleochroism, zoning, inclusions, fractures, usable yield and optical potential before committing valuable material to the lap.
Discover how ruby and sapphire form deep within the Earth. Explore the geology of corundum, from metamorphic and magmatic environments to the geological processes that create gem-quality ruby and sapphire.
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.
