Peacock Opal — Dark Opal with Multicoloured, Peacock-Plumage Play-of-Colour
Peacock Opal — Dark Opal with Multicoloured, Peacock-Plumage Play-of-Colour
A descriptive trade term for premium black opals dominated by blue-green-violet flashes on a dark body
Peacock opal is a descriptive trade term for black or dark opal whose play-of-colour is dominated by saturated blue, green, and violet flashes on a dark body tone, recalling the multicoloured iridescence of peacock plumage. The term is not a formal mineralogical variety; it describes a specific play-of-colour pattern within the dark-opal category, predominantly produced at the Lightning Ridge field of New South Wales, Australia. Peacock opals command premiums above single-colour and pale play-of-colour examples and sit near the top of the commercial opal hierarchy.
What peacock opal is
The opal trade grades opals on body tone, brilliance, pattern, and play-of-colour spectrum. Body tone runs from N1 (very dark black) through N9 (white) on the standardised Australian scale, with N1 to N4 designated as black opal proper, N5 to N6 as dark opal, and the higher numbers as light or white opal. Peacock opal is typically a black opal in the N1 to N4 range whose play-of-colour pattern is dominated by the cooler end of the spectrum — particularly the saturated blue, blue-green, and violet flashes — with sufficient warm-end colour (red, orange, gold) present that the overall effect rotates through the peacock palette as the stone is tilted.
Lightning Ridge produces the principal supply of peacock-pattern opal. The Mintabie field in South Australia, the Coober Pedy fields, and the Mexican opal fields produce occasional peacock-pattern stones, but the dark body tone characteristic of true peacock opal is most consistently associated with Lightning Ridge. Ethiopian Welo opals can produce broad-flash, multicoloured play-of-colour, but their light body tone places them in a different commercial category from peacock opal in the strict sense.
The structural basis
Opal's play-of-colour arises from light diffraction at regular arrays of submicroscopic silica spheres. The size of the spheres determines which wavelengths diffract: larger spheres diffract red and warm wavelengths, smaller spheres diffract blue and cool wavelengths. The peacock palette — dominated by blue and green with strong violet — corresponds to sphere sizes in the lower end of the diffracting range. The dark body tone, which is essential to the peacock effect, comes from the dark common-opal matrix surrounding the diffracting layers; without the dark background, the cool flashes lose contrast and the peacock palette flattens.
Pattern and grading
The trade recognises several play-of-colour patterns, including pinfire, harlequin, broad flash, ribbon, and rolling flash. Peacock opals most often present in broad-flash or rolling-flash patterns, where colour patches are large enough — typically more than three millimetres — to read as discrete flashes rather than as the small dots of a pinfire pattern. Pattern size and clarity contribute substantially to value; large, well-defined patches command premiums over small or chaotic patterns of equivalent body tone and saturation.
Care and trade
Opal of all kinds is sensitive to mechanical impact and to thermal shock. Hardness of 5.5 to 6.5 on the Mohs scale and the presence of trapped water in the silica structure place opal among the more delicate gem materials. Daily-wear ring use is generally inadvisable for fine peacock opal; pendant and earring applications are preferred. Cleaning should be by mild soap and lukewarm water; ultrasonic and steam cleaning are not recommended.
Pricing for fine peacock opal varies widely with body tone, brilliance, pattern size, and saturation. Top examples from Lightning Ridge can exceed ten thousand dollars per carat for stones above one carat; commercial-quality peacock opal at smaller sizes is widely available at lower price points.