Where does brilliance collide?

In gemology, brilliance is the brightness of a cut gem (the amount of white light that enters through the crown, reflects off the pavilion facets by total internal reflection, and returns to the viewer's eye), and it is judged separately from fire (spectral colors) and scintillation (sparkle). Webster's Gems: Their sources, descriptions and identification explains that brilliance depends chiefly on the stone's refractive index, its proportions, and the quality of its polish, which together decide how much light is returned rather than leaked out the back. The referent is the returned-light brightness of a worked gemstone, a property of cut and material, distinct from an intellectual trait or a beam's figure of merit.[1]

Unit

The proportion of incident white light returned to the eye

Recovery means

Not applicable

Measured by

Assessed in cut grading by light return, with proportions and polish as the governing variables

In synchrotron and x-ray physics, brilliance (also called brightness) is a figure of merit for a radiation source that combines photon flux with how tightly the beam is collimated and focused: the number of photons emitted per second, per unit source area, per unit solid angle, within a narrow relative bandwidth. Als-Nielsen and McMorrow's Elements of modern X-ray physics defines this measure and uses it to compare sources, since a high-brilliance beam concentrates many photons into a small, low-divergence spot. The referent is a quantitative beam-quality metric with definite units, unrelated to a sparkling gem or a person's intellect beyond the shared word.[2]

Unit

Photons per second per mrad² per mm² per 0.1% bandwidth

Recovery means

Not applicable

Measured by

Computed from photon flux, source size, beam divergence, and spectral bandwidth

In social psychology, brilliance names a field-specific ability belief: the shared assumption, stronger in some academic disciplines than others, that success demands a raw, innate intellectual gift that cannot be taught. Leslie, Cimpian, Meyer, and Freeland's 2015 Expectations of brilliance underlie gender distributions across academic disciplines measured how strongly practitioners in each field endorse this belief and found that fields prizing brilliance have fewer women and fewer African Americans, consistent with stereotypes about who possesses such gifts. The referent is a measurable cultural belief about the kind of mind a field requires, a construct in social cognition rather than an optical property of light.[3]

Unit

The strength of field-level endorsement that success needs innate talent

Recovery means

Not applicable

Measured by

Measured by survey items rating how much a field requires innate talent, aggregated to a field-level score