Australia, Mexico, Ethiopia, and Brazil: four palettes of light
Opals are found in several parts of the world, but not all opals are equal. Each producing region gives the gem distinct characteristics, shaped by the specific geological conditions of each territory. Understanding these differences is essential for anyone who wants to know, collect, or work with opals with genuine expertise.
Australia: the historical market benchmark
Australia has been the world's largest opal producer for centuries, at certain periods accounting for approximately 95% of the global market. The main producing regions are Lightning Ridge (black opals), Coober Pedy (white and crystal opals), and White Cliffs. The black opal of Lightning Ridge is considered the most valuable in the world: the dark background dramatically intensifies the play of colors.
Mexico: fire in the stone
Mexico is the origin of the celebrated fire opals, found primarily in the state of Queretaro. Distinguished by warm background tones of orange and red, they may or may not display an internal play of colors. Unlike Australian and Piauí opals, Mexican opals have a volcanic origin, hosted in rhyolites and igneous rocks.
Ethiopia: the new player that reshaped the market
From 2008 onward, the discovery of opal deposits in Ethiopia, especially the Welo opals, significantly altered global market dynamics. These opals display exceptional play of colors and are available in considerable volumes. A unique characteristic is hydrophany: they absorb water and can temporarily alter their transparency upon contact with liquids.
Brazil (Piauí): a distinct identity
The opals of Pedro II are formed in sedimentary sandstones of the Parnaíba Basin and have developed their own aesthetic: high transparency, variety of types, stability, and saturated colors.
Which to choose?
There is no single answer. Each origin produces a different aesthetic experience. What matters above all is knowing the provenance, understanding what you are acquiring, and choosing the gem that carries the narrative most aligned with what you want to express.
Source: GOMES, C.B. et al. As Opalas do Piauí [The Opals of Piauí]. Brasília: CETEM/MCTI, 2025. Part of Fortes Jewellery's educational gemology series, based on scientific research by the Centro de Tecnologia Mineral of Brazil's Ministry of Science, Technology and Innovation.