Why does tourmaline grow in pegmatites, ruby occur in marble, emerald form through fluid-rock interaction and diamonds come from the mantle? Explore the geological environments and processes that create natural gemstones.
Inclusions are more than imperfections. Mineral crystals, fluids, negative crystals, rutile silk, fingerprints and growth features can preserve evidence of how a gemstone formed, whether it was treated and sometimes where it may have originated.
A refractometer, microscope and spectroscope can answer many gemstone questions—but not all of them. Explore how modern laboratories use Raman, FTIR, UV-Vis-NIR, photoluminescence, XRF and LA-ICP-MS to investigate identity, treatments, synthetics and geographic origin.
Four sapphires can share essentially the same RI, SG and optical character yet have radically different histories and values. Follow an advanced evidence-based workshop separating natural unheated, heated, synthetic and diffusion-treated sapphire.
An unknown green gemstone could be emerald, tourmaline, peridot, tsavorite or even glass. Follow a realistic evidence-based investigation using refractive index, birefringence, optical character, pleochroism, spectroscopy, specific gravity and microscopy.
Discover ruby from a gemmologist’s perspective: how this red variety of corundum forms, why chromium creates its colour and fluorescence, and how refractive index, inclusions, spectroscopy and other diagnostic properties help identify it.
Five blue gemstones can look deceptively similar. Work through a realistic gemmological investigation using refractive index, birefringence, polariscope, dichroscope, specific gravity, spectroscopy and microscopy to identify the unknown stone.
A red gemstone is placed on the gemmologist’s desk with no identification. Is it ruby, spinel, garnet or glass? Work through the evidence step by step using refractive index, optical character, spectroscopy, specific gravity and microscopy.
Gemstone identification is not based on one test. Learn how gemmologists progressively combine observation, microscopy, refractive index, optical character, pleochroism, spectroscopy and specific gravity—and when advanced laboratory testing becomes necessary.
Gemstone Specific gravity adds a non-optical measurement to gemstone identification. Learn how hydrostatic weighing works, calculate SG from weights in air and water, avoid common errors and combine density with refractive index and microscopy.
