Undeniably beautiful and rare, Brazilian Opal’s signature color-play, fine-quality, and durability, are favorably comparable to Australian Opal, arguably the world’s finest. Appearing to have a rainbow trapped within, Brazilian Opal comes from the famous Opal fields of Pedro II (Pedro Segundo, for the last Brazilian Emperor), in the state of Piauí (Pi-ah-wi). Discovered in the 30s, by the early 80s, almost 70 percent of its mines had closed! While small groups still sporadically mine, Brazilian Opal’s well past its peak, keeping these beautiful, exceedingly scarce, color-play Opals, highly-valued by savvy aficionados.
Hardness 5.5 – 6.5
Refractive Index 1.370 – 1.520
Relative Density 1.98 – 2.50
Enhancement None
Beauty
Unique to Opal, ‘play of color’ are beautiful colorful flashes that change with the angle of observation. When white light enters the top of an Opal, it refracts and bounces around inside, through all the microscopic spheres and gaps between them. As the light passes through Opal, it diffracts like a prism, splitting the white light into all the colors of the spectrum. The light eventually bounces back out the top of the gem, giving us an eyeful of beautiful colors. While Ammolite and Labradorite split light through lattice layers, Opal is the only gemstone that diffracts light in this way. The diameter and spacing of the spheres control the color range of an Opal, with the size and angle at which light is split determining the color produced. The color rarity hierarchy’s red, orange, yellow, green, blue and violet, with value lying in the brilliance, brightness, and strength of colors displayed. For example, the rare reds and oranges are reflected from the scarcer smaller spheres, approximately 3,500 angstroms in diameter, while Opal’s blues are reflected from the more common larger spheres, about 1,500 angstroms in diameter. The rest of the colors of the rainbow occur between these sizes. Opals that display red can also display all the other colors of the spectrum, but… even though the presence of red increases an Opal’s rarity and value, it’s typically valued lower than one that shows several colors. The patterns of color also affect value, with large patches of color priced higher than those with small patches of color. An Opal with a play of color comprising more than half of one color is named for its primary hue, while an Opal with three or more hues is called ‘multicolor’. The most artistic gemstone, each Opal has its own color personality, keeping individual tastes important.
Opals are classified by their host-rock (also known as ‘matrix’ or ‘potch’) on which Opal forms, and their resulting transparency, and body color (the base color on which Opal’s color play is visible), with transparency demanding a premium in lighter colored Opals (White, also known as ‘Light Opal’, and Jelly, crystal Opal without host-rock). Similar in appearance to Coober Pedy White Opal from South Australia, Brazilian Opal is translucent to opaque with a white body color, showing a vibrant, full-spectrum play of color in a range of highly-desirable patterns including, broad flash/flag, floral, harlequin, pinfire, and rolling flash.
Deft lapidary that accentuates Opals’ innate beauty and signature color play is absolutely critical. Optimally cut at dedicated lapidaries in the legendary Brazilian Opal-municipality in which they were mined, Pedro II, as well as the internationally acclaimed gemstone country of Thailand (Siam), both home to some of the world’s very best gem cutters. Every Opal in this collection has been expertly cut ‘en cabochon’ (cut in convex form and highly polished, but not faceted) by experienced lapidaries, with a superior mirror-like polish/luster, desirable finish, and an excellent overall appearance (outline, profile, proportions, symmetry, and shape).
An October birthstone, Opal is from the Greek ‘opallios’, meaning ‘to see a change’, and is comprised of silica and water, the main component in glass. When silica under the earth mixes with water, a silica solution forms. If this solution fills voids or is trapped in layers under the earth, Opal begins to form. The structure of Opals is unique and comprised of microscopic silicon dioxide spheres (1,500 – 3,500 angstroms in diameter; 1 angstrom is 1 ten millionth of 1 millimeter) that form a pyramid shaped grid, interspersed with three to six percent water. It’s the refraction of light through these spheres and the gaps between them that produce Opals’ characteristic ‘play of color’. Opal without play of color has its silicon dioxide spheres more randomly arranged.
Rarity
While fine, color-play Opal is not generally associated with South America, beautiful Opal has long been unearthed in the Brazilian states of Pará, Piauí, Rio Grande do Sula, and Rondônia. With most deposits nearing depletion, mining is usually very limited and sporadic, making Brazilian Opal difficult to secure. Brazil’s most famous, fine-quality, color-play Opal deposits are located in the northeastern state of Piauí in the Pedro II municipality. Pedro II (Pedro Segundo, for the last Brazilian Emperor, Don Pedro Segundo) is primarily an agricultural region around 700 meters above sea level, with a cool climate.
Our Brazilian Opal was sourced by internationally renowned gem professional and lapidary, Mark ‘The Opal Hunter’ Tremonti, an Australian gemstone legend. For over 40 years, he’s been mining, cutting and trading some of the finest Opals, colored gems, and Diamonds, Australia and the world has to offer, direct from the source. Visiting Pedro II since 1994, Mark’s close relationships with local mining families, allowed him to partner with an international group in 2023, creating a new, mine-to-market network for Brazilian Opal, with exceptional mine-level value afforded by vertical-integration. Extremely important in today’s gem and jewelry marketplace, nothing is lost to unnecessary middlemen, and provenance is assured.
Opals were reportedly first found at Pedro II in the late 30s. Awareness dramatically increased in the 60s, with Jules Roger Sauer (1921 – 2017), founder of the iconic Amsterdam Sauer jewelry chain, promoting Brazilian Opal. Sauer was a true gem adventurer who significantly contributed to the growth of Brazilian gemstones. Interestingly, according to folklore, unaware of their true value, locals initially used these Opals as buttons! At its peak in the 60s and 70s, there were more than 30 mines, but by the early 80s, almost 70 percent had closed due to depletion. While small groups of miners still sporadically work the municipality, it’s well past its ‘golden age’, with most mining small-scale artisanal, done by hand.
The Opal fields are mainly located approximately 20 square kilometers around Pedro II, with ours from the Roça (Roh-kah) Claim, a primary host-deposit (see below). Other notable occurrences in the municipality include, Barra, Boi Morto Mine, Bom Lugar, Cantinho, Centro Dos Gomes Claim, Chã Do Lambedor Deposit, Corrente Creek, Limão, Mamoeiro Claim, Morro Do Meio, Pajeú Claim, Pirapora, and Rio Dos Matos. Similar to Australian Opal, Pedro II Opals are sedimentary, and are mined both alluvially, where Opals occur as ‘nuggets’ amongst the stratum, as well as primary deposits, where Opals are found as veins in the host sedimentary sandstone, or as thin layers attached to intrusive dikes (tabular, sheet-like igneous bodies cutting across existing rock layers). At alluvial deposits, miners wash and manually extract Opal, while excavators are used to remove the overburden (rock/soil overlying a mineral deposit) to reach host seams, before extracting the Opal by hand. Excavators are also used in the reclamation of former mines. While local miners typically alternate between Opal mining in the dry summer, and farming during the rainy season, akin to visitors to Coober Pedy and Lightning Ridge, tourisms also important. To support their community, miners allow locals to freely use Opal tailings (left-over mining material) to create mosaic tourist souvenirs.
With the gemology, quality and stability of Brazilian Opal’s comparable to fine Coober Pedy White Opal, it was once historically (and deceptively) sold as ‘Australian’ in the marketplace, which is especially disappointing considering Brazil is proud of their Opal quality. To ensure Brazilian Opal is properly represented, the Brazilian government has granted Piauí Opal the region characteristic, ‘Geographical Indication Certificate’, helping generate revenue to support local mining communities.
Brazilian Opals’ scarcities significantly impacted by a highly-variable and unpredictable cut yield. Depending on the size and color of the Opal seams between the host-rock sedimentary layers, cut yields range from a low of 8 percent, to a high of 33 percent, noting the usual gem mineral return’s 20 – 35 percent. Importantly, our Brazilian Opals are totally natural, solid and unenhanced, accentuating desirability, rarity, and value. Brazilian Opal that’s too thin for calibration or freeform singles are often used to make doublets, by gluing a thin Opal layer to a dark base.
Source: Gems & Gemology, Spring 2024, Vol. 60, No. 1, ‘Precious Opal from Pedro II, Brazil’ by Tao Hsu.
Durability & Care
Their colorful brilliance aside, Brazilian Opals are also coveted for their hardness and stability, a key consideration for a gem containing three to six percent water. A relatively durable jewelry gemstone, Brazilian Opal (Mohs’ Hardness: 5.5 – 6.5) should always be stored carefully to avoid scuffs and scratches. Clean with gentle soap and lukewarm water, scrubbing behind the gem with a very soft toothbrush as necessary. After cleaning, pat dry with a soft towel or chamois cloth.
Map Location
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