iridescence

"But as these faces, different in this respect from those of the party around me, were not overlaid for me by any residue of physical experience or social mediocrity, they remained, in their handsome outlines and rainbow iridescence, homogeneous with those names which at regular intervals, each of a different hue, detached themselves from the genealogical tree of Guermantes, and disturbed with no foreign or opaque matter the translucent, alternating, multicoloured buds which like the ancestors of Jesus in the old Jesse windows, blossomed on either side of the tree of glass."
--The Guermantes Way by Marcel Proust, translated by C.K. Scott Moncrieff and Terence Kilmartin, Revised by D.J. Enright, p 744 of the Modern Library paperback edition

Related words from the OED:

iridesce (v. intr.)
To exhibit iridescence; to shine in an iridescent manner.

1905 J. LONDON Jacket (1915) 48
Sun-flashed water where coral-growths iridesced from profounds of turquoise deeps.

iridescent (a.)
Displaying colours like those of the rainbow, or those reflected from soap-bubbles and the like; glittering or flashing with colours which change according to the position from which they are viewed.

1879 G. ALLEN Colour-Sense i. 5
We do not owe to the colour-sense the existence in nature of the rainbow, the sunset, or the other effects of iridescent light.

1873 BLACKIE Self-Cult. (1874) 84
The best fictions, without a deep moral significance beneath, are only iridescent froth.

iridian (a.)
Rainbow-like; brilliantly coloured.

1888 A. UPWARD Songs in Ziklag 146 Consistency ii,
Truth's iridian arch.

iridical (a.)
Brilliant with rainbow colours.

1862 S. LUCAS Secularia 100
The iridical window and the flaming shrine.

iridine (a.)
Rainbow-like; iridescent.

1851 S. JUDD Margaret I. xiv. (Ward & Lock) 110
The horned-pout, with its pearly iridine breast and iron-brown back.

iridize (v. trans.)
To make iridescent.

iridization (n.)
The action or process of showing prismatic colours as in the rainbow; irisation.

1884 Pop. Sci. Monthly June 288
M. Cornu lately described to the French Academy of Sciences a white rainbow...This rainbow was wholly white, without even as much iridization as is noticeable in halos, and had a fleecy appearance.