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The way a gemstone is cut determines how much of the light entering it is returned to the eye. We study the relationship between facet arrangement, angles and the visual effects observers describe as brightness, fire and scintillation.
Findings are expressed in practical terms that connect measurable proportions with what is actually seen.
Crown and pavilion angles, table size, depth and girdle thickness are measured and compared across cutting styles.
Understanding why stones of the same weight and material can look very different.
Links specific proportion ranges to observed appearance.
Structured-light viewers show where a stone returns light, where it leaks and where the observer's reflection darkens it.
Comparing brilliant, step and mixed cuts under the same conditions.
Gives a visual, comparable record of optical performance.
Computer models follow light paths through a virtual stone built from measured proportions.
Testing how small changes in angle affect overall light return.
Allows many variations to be explored without recutting.
Brightness is the white light returned to the eye. Fire is the separation of that light into spectral colours through dispersion.
Not exactly. Refractive index differs between species, and coloured stones are also oriented for best colour, so ideal proportions vary.
Proportions are a strong guide, but symmetry, polish and the material itself also contribute, so direct observation remains important.
Establishing species and variety through optical, physical and spectroscopic measurement.
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Consistent description of colour, clarity, cut and weight under controlled conditions.
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Locating and modelling internal features in rough and polished stones.
Read MoreAdvancing the understanding of gemstones through science, precision and innovation, from their formation deep within the Earth to the finished stone.
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