It has a kind of ethereal appearance when it reflects light due to its iridescence.
The common opal is often opaque and displays very little iridescence, where as the precious opal has many flashes of color.
Pearl gemologists estimate there may be as many as 40 shades of black, from light gray to rich ebony, all of which have deep layers of color and iridescence to add to their mystique.
For the culture of the Roman period there is abundant evidence from Salamis and Paphos, and from tombs everywhere, for the glass vessels which almost wholly supersede pottery are much sought for their (quite accidental) iridescence; not much else is found that is either characteristic or noteworthy; and little attention has been paid to the sequence of style.
Rest assured that even the boldest reds now usually contain an iridescence that makes them less harsh and easily wearable by women of varying skin tones.
