Where did your gemstone really come from- and how can anyone know? Discover how gemmologists investigate gemstone provenance using inclusions, spectroscopy, trace-element chemistry and reference collections. Learn the differences between mining origin, trading location, laboratory origin opinions and documented traceability, with practical guidance for interpreting gemstone reports and buying with confidence.
Why do some natural gemstones contain bands, patches or sharply defined areas of different colours? Explore the science of gemstone colour zoning, from trace-element variations and crystal growth to sapphire, tourmaline, amethyst and fluorite. Learn how gemmologists interpret these patterns, how cutters work with uneven colour distribution, and why colour zoning can sometimes reduce value while making other gemstones exceptionally desirable.
Heat treatment can transform the colour and clarity of natural gemstones without necessarily changing their mineral identity. Explore the science behind heated sapphires, rubies, aquamarines, citrines and other gemstones. Learn how temperature, atmosphere, trace elements and inclusions influence treatment results, how professional laboratories investigate heating and why accurate disclosure is essential when buying natural gemstones.
Is a harder gemstone always more durable? Not necessarily. Discover the scientific differences between hardness, toughness, cleavage and stability, and learn why diamond can chip, topaz can split and jade can resist powerful impacts. An essential guide to understanding gemstone durability and choosing natural gemstones for jewellery and collecting.
Why does a gemstone appear green in daylight but red under incandescent light? Explore the science of gemstone colour change, from selective absorption and human colour perception to alexandrite, colour-change garnet and sapphire, including how gemmologists distinguish the phenomenon from pleochroism.
Some gemstones appear green in daylight but red or purple under incandescent lighting. This fascinating phenomenon is not caused by magic or a change in chemical composition. Discover how selective light absorption, trace elements and illumination interact to create the extraordinary colour changes observed in alexandrite, sapphire and garnet.
Alexandrite can appear green in daylight and reddish purple under incandescent light. Some garnets, sapphires and other gems can also change colour. Discover why the effect depends on both a gemstone’s absorption spectrum and the light illuminating it—and why colour change must not be confused with pleochroism.
Ruby, sapphire, tourmaline, iolite and tanzanite can change colour as viewing direction changes—not because their chemistry changes, but because their crystals absorb light differently along different directions. Discover the science and practical gemmology of pleochroism.
Gemstone colour is far more complex than “trace elements cause colour.” Discover how crystal fields, transition metals, charge transfer, lattice defects and physical optics transform ordinary white light into ruby red, emerald green, sapphire blue and the extraordinary colours of the gem world.
Diamond is the hardest gemstone, but hardness alone does not determine durability. Discover the crucial differences between scratch resistance, toughness, cleavage and stability—and why they matter when choosing, wearing and caring for gemstones.
