Why do diamonds, demantoid garnets and titanite display spectacular rainbow flashes? Explore the science of gemstone dispersion and fire, the role of refractive index, cutting proportions and illumination, and the essential differences between brightness, fire and scintillation. Episode 10 of the Natural Gems Belgium Gemmology Series explains the physics behind these remarkable optical effects.
How can gemmologists distinguish gemstones that look almost identical? Discover the science of refractive index, Snell's law, critical angles and professional refractometer measurements. Episode 9 of the Natural Gems Belgium Gemmology Series explains how light helps identify gemstones - and why one measurement is never the complete answer.
Why do some gemstones display moving stars or brilliant cat's-eye bands? Explore the science of asterism and chatoyancy, from microscopic inclusions and crystal structure to cabochon cutting, optical examination and gemstone identification. Episode 8 of the Natural Gems Belgium Gemmology Series explains these remarkable natural optical phenomena.
Why do some gemstones glow under ultraviolet light? Discover the science of gemstone fluorescence, electronic excitation, activators, quenching and phosphorescence, with examples from ruby, sapphire and diamond and an explanation of how fluorescence supports professional gemmological identification.
Why can one gemstone show different colours from different directions? Explore the science of pleochroism, dichroism and trichroism, and discover how crystal structure, selective absorption, the dichroscope and cutting orientation influence gemstone colour.
What does eye-clean really mean? Explore gemstone clarity, inclusions, transparency, magnification and durability, and learn why clarity must be evaluated differently across emerald, ruby, sapphire, aquamarine and other coloured gemstones.
Gemstone inclusions are more than imperfections. Mineral crystals, fluids, growth structures and healed fissures can preserve evidence of formation, treatment and origin. Discover how gemmologists interpret the microscopic world inside natural gemstones.
Natural, synthetic and simulant gemstones can look remarkably similar while having fundamentally different origins and properties. Discover how gemmologists distinguish them using growth features, inclusions, optical properties and advanced laboratory testing.
Gemstone treatments can alter colour, clarity and appearance without making a natural gemstone synthetic. Explore heating, emerald oiling, fracture filling, dyeing, irradiation and coatings, and learn why proper treatment disclosure matters.
