Opal can vary dramatically in colour, pattern, construction and stability. Lena Hoffmann explains how to evaluate play-of-colour, distinguish solid opal from doublets and triplets, understand hydrophane material and treatments, recognise crazing and know what to ask before buying.
Discover peridot through professional gemmology. Explore how this magnesium-rich olivine forms deep in Earth's mantle, reaches the surface in basalt or tectonic ultramafic rocks, and reveals its identity through strong birefringence, iron-related spectroscopy, lily-pad inclusions and trace-element chemistry.
Buying tanzanite requires more than choosing the deepest blue stone. Lena Hoffmann explains in this video how colour, pleochroism, cutting direction, heat treatment, clarity, durability and non-standard quality grades can influence what you are actually buying.
Discover the gemmology of elbaite with the Nadia Gemstone academy video series. Elbaite, a lithium-rich tourmaline species renowned for its remarkable colours and complex crystal chemistry. Explore its pegmatitic formation, optical properties, internal zoning, diagnostic spectroscopy, treatments and laboratory identification, including the science behind copper-bearing Paraíba-type material.
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.
Buying an emerald is about much more than finding the cleanest green stone. Lena Hoffmann explains how to assess colour, understand natural inclusions and clarity enhancement, evaluate treatment disclosure, question origin claims and know when an independent laboratory report matters.
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.
Explore chrysoberyl through professional gemmology. Learn how its beryllium aluminium oxide structure, geological formation and trace-element chemistry produce yellow-green gems, colour-changing alexandrite and cat's-eye chrysoberyl. Examine diagnostic optical properties, microscopy, spectroscopy, synthetic materials and durability.
Discover the mineralogy and gemmology of topaz. Explore its orthorhombic crystal structure, fluorine–hydroxyl chemistry, optical properties, geological formation, chromium-related colours, irradiation treatments and microscopic identification. Learn why its perfect basal cleavage is one of its most important diagnostic and durability characteristics.
