Iridescence

n.joyful, calmliterary

What it means

A shifting display of colors that changes with the angle of view or illumination.

Reach for it when describing an optical color effect rather than a fixed rainbow palette

Iridescence moved across the shell as the curator tilted it toward the light.

playful
color play
informal description should stress changing hues
not when Color play leaves the optical mechanism unspecified.
everyday
rainbow sheen
plain language should describe multicolored surface light
not when Rainbow sheen can imply fixed bands rather than angle-dependent color.
warm
shimmer
small moving flashes of light are the visual effect
not when Shimmer may be colorless and does not require hue to change with angle.
professional
pearlescence
a soft nacre-like luster is the specific finish
not when Pearlescence is typically pale and narrower than iridescence.
formal
luster
surface reflection and brightness are central
not when Luster can be a single color and lacks iridescence's shifting hues.
literary
opalescence
a milky play of shifting color resembles opal
not when Opalescence is softer and more cloudy than many iridescent surfaces.

subtle iridescence
A subtle iridescence appeared along the beetle's wing case.
natural iridescence
Natural iridescence made each feather look different as the light moved.
show iridescence
The glaze begins to show iridescence under a narrow beam.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.