Why can a diamond chip despite being the hardest natural mineral? Why does topaz sometimes split along a smooth plane, and why must kunzite and fluorite be handled carefully? Explore the science of gemstone cleavage, fracture and toughness, with practical advice for rough crystals, faceted gemstones, jewellery settings and mineral collections.
Every finished gemstone begins with a series of decisions made before cutting starts. Discover how professional lapidaries evaluate natural rough gemstones, select the most suitable cutting orientation, manage inclusions and colour zoning, calculate potential yield and balance beauty against weight retention. A practical guide to the science and craftsmanship behind gemstone cutting.
What makes a gemstone cabochon well cut? Discover how to assess dome symmetry, proportions, polish, surface condition and optical effects. This practical gemmology guide explains how to evaluate ordinary cabochons, moonstones, star sapphires, cat's-eye gemstones and opals using professional assessment principles supported by scientific research.
A gemstone can appear different in photographs, videos and real life—even without digital manipulation. Explore how lighting, camera settings, backgrounds and screen technology influence gemstone colour, clarity and brilliance. Learn how to evaluate gemstone photographs and make better-informed purchasing decisions.
Why does a gemstone cutter sometimes remove more than half the original rough? Discover how natural crystal shape, inclusions, colour zoning, optical physics and cutting proportions influence the transformation from rough gemstone to finished gem—and why a smaller stone can sometimes be significantly more valuable.
A laboratory report can establish important facts about a gemstone, but it does not automatically tell you its quality, market value or whether you should buy it. This practical NGB guide explains each major section of a coloured-stone report and the limitations every gemstone buyer should understand.
A 10× loupe can reveal far more than inclusions. Learn a systematic gemstone examination workflow—from cleaning and surface inspection to darkfield microscopy, fibre-optic lighting, inclusion depth, fractures, growth structures and the limits of visual identification
Ruby and red spinel can look remarkably similar—and history repeatedly confused them. Follow a professional identification workflow using refractive index, optical character, specific gravity, fluorescence, spectroscopy and microscopy.
Three green stones. All are emerald. Only one formed naturally. Follow a professional evidence-based investigation using refractive index, specific gravity, dichroism, microscopy, growth structures and advanced laboratory analysis.
A colourless brilliant-cut stone arrives without documentation. Is it diamond, synthetic moissanite or cubic zirconia? Follow the evidence through magnification, optical properties, thermal testing and advanced laboratory screening.
