Editors

Precious and imperial topaz from Brazil

EditorsJan 25, 2013

Precious and imperial topaz from Brazil

Brazil produces more topaz than any other country in the world. Most of the production is colorless, which is irradiated and heated into various shades of blue. Precious and imperial topaz offer a rare and warmer alternative to the cool blue shades we are accustomed to seeing in jewelry stores. “Precious” topaz usually refers to yellow to orange colors while “imperial” topaz usually refers to pinkish-orange to pink to purple and even red colors (see figs. 1 and 6).  However, some dealers argue that all topaz in these warmer hues should be classified as imperial. Since the origin of the word topaz is most likely from the Sanskrit word “tapas,” meaning fire, this argument seems to have merit. Recent price increases are due to limited mining, renewed interest from designers in these warmer hues and strong domestic demand in Brazil.



Fig.1: Precious and imperial topaz from Ouro Prêto, Brazil (Gems from 5 carats to more than 62 carats)
Center: Classic orthorhombic crystal with prismatic termination (102g). Photo: E. Boehm, RareSource

No visit to Brazil would be complete without stopping by the famous gold mining region of Ouro Prêto, “Black Gold” in reference to the black rock in which gold was first discovered there during the Brazilian gold rush of the early 18th century. Today, this beautifully preserved colonial Portuguese city is a UNESCO World Heritage Site and the world’s only source for imperial topaz.

Ouro Prêto, while built on gold mining, is today more famous for precious and imperial topaz, which was also discovered here in the early 1700s. The topaz mines are located just a short drive outside the city so it is possible to visit them in a few days. Getting there is easier if one flies through the closest major airport in Belo Horizonte, which is only a two- to three-hour drive from Ouro Prêto.

The two main large-scale mines of Capão and Vermelhão produce the majority of all material on the market today but there are also several small-scale mines operated by independent artisanal miners known as Garimpeiros. Vermelhão is the Portuguese word for vermilion in reference to the reddish-orange to red topaz crystals found there. All the mines are open-pit operations that use water to separate the gem crystals from the weathered host rock.


                              

Fig.2: Washing grate (top left) used for the initial separation of host rock and gem-bearing ore, which flows down the slope to the rolling jig that further separates the gems from the ore. Capão Imperial Topaz Mine, Brazil.
Photo: E. Boehm, RareSource

Fig.3: Fine topaz crystals (top right) displaying the orange to sherry range of color found at the Capão mine in Ouro Prêto, Brazil. Photo: E. Boehm, RareSource


Fig.4: Topaz crystals ranging from golden yellow to vivid pink. Photo: E. Boehm, RareSource

Geology
Topaz is an alumina-silicate that typically forms in granitic pegmatites or rhyolitic igneous rocks.  Imagine a molten volcanic material that travels from the lithosphere deep in the earth through the asthenosphere and ultimately into the Earth’s crust. This molten material either migrates up as a large plutonic mass, or squeezes into weaker fractured areas within the earth’s crust creating pegmatites, or explodes out in the form of a volcanic rhyolite. Once it
hits the solid crust or is exposed to the surface, it cools and crystallizes. There are two parts to this crystallization process. The first is the pegmatitic phase, which may also involve the mixing of the surrounding crust’s minerals with the molten intrusive pegmatite. The second is the hydrothermal phase, which involves the introduction of mineral-rich fluids into the pegmatite. This is a very basic explanation of the extremely complex nature of how petrological forces effect the formation of various pegmatite minerals such as topaz.



Fig.5: Topaz crystals in host rock from the Vermelhão Mine in the Saramenha district of Ouro Prêto within the state of Minas Gerais, Brazil. Photo: E. Boehm, RareSource

Gemology
The basic chemical formula for topaz is Al2(SiO4)(F,OH)2.  Precious and imperial topaz gets its colors from trace amounts of chromium (Cr+3). It has a relatively high hardness of eight on the Mohs scale, which is the same as spinel. Like diamond, it has one direction of perfect cleavage so care must be taken to avoid hard blows. Its relatively high refractive index (1.61-1.63) and excellent transparency make topaz one of the most versatile and desirable gems. Like tanzanite and chrysoberyl, topaz is no-axial which means it has two optic axes and three optical directions through which light travels at different speeds. These three optical directions represent the three refraction indices of topaz. This also means that each direction has a different absorption producing different colors. Blending these colors in the faceting process is a true art and can produce amazingly varied results, particularly in precious and imperial topaz. Topaz typically contains two-phase inclusions (liquid and gas), three-phase inclusions (crystal, liquid and gas), or multi-phase inclusions (crystals, liquids and gas). These multi-phase inclusions are a result of the hydrothermal phase during which crystal growth occurs.


Fig.6: An extremely rare 17-carat imperial red topaz, square cushion, Ouro Prêto, Brazil Gem Courtesy RareSource, Photo by R. Weldon

Graduate Gemologist (G.G.) Edward Boehm is the owner of RareSource (formerly JOEB Enterprises), a Chattanooga, Tenn.-based gemstone supply and consultancy. RareSource travels to mines worldwide to bring customers the finest quality gemstones. Contact him at edward@raresource.com. For those attending the Tucson show next month, please feel free to drop by the RareSource booth #406 at the AGTA show.
Edward Boehmis a Graduate Gemologist and the owner of colored gemstone and supply consultancy RareSource.

The Latest

Elton John’s leopard print Rolex Daytona watch
AuctionsFeb 22, 2024
Elton John’s Leopard-Print Rolex Roars at Auction

Two Cartier watches also topped their estimates at Christie’s “The Collection of Sir Elton John: Goodbye Peachtree Road” evening sale.

Buccellati header
TrendsFeb 22, 2024
Buccellati to Open ‘Prince of Goldsmiths’ Exhibition

Set to be held in Venice, it’s a look through the maison’s history.

813-carat “Constellation” diamond in rough form
SourcingFeb 22, 2024
Lucara, HB Group Partnership Revived

It is another 10-year sales agreement in which all the larger rough recovered from the Karowe mine will go to HB Group for manufacturing.

GIA id100
Brought to you by
Full Disclosure at Your Fingertips

Distinguishing natural diamonds from laboratory-grown stones – now more available than ever – has been difficult for jewelers. Until now.

Sebastian Clarke and Katherine van Dell of Heritage Auctions
AuctionsFeb 22, 2024
Heritage Auctions Adds 2 New Hires to West Palm Beach Office

Sebastian Clarke and Katherine van Dell, frequent appraisers on “Antiques Roadshow,” will join the new office.

Weekly QuizFeb 22, 2024
This Week’s Quiz
Test your jewelry news knowledge with this short test.
Take the Quiz
National Jeweler columnist Sherry Smith
ColumnistsFeb 21, 2024
On Data: January Was a ‘Mixed Bag’ for Independent Jewelers

Sherry Smith dishes on the month’s highs and lows and the two categories consumers were loving ahead of Valentine’s Day.

Stock image of diamonds
GradingFeb 21, 2024
GIA’s Same-Day Service Now Available Everywhere

The new service, introduced to stem fraud related to lab-grown diamonds, will be offered at no cost for the time being.

flashforge pic.png
Brought to you by
WaxJet: Revolution in Jewelry Manufacturing

The WaxJet 400, recognized as the world's fastest wax printer, is bringing in a new era of precision and efficiency to industry.

Jam + Rico Claire’s jewelry
CollectionsFeb 21, 2024
Jam + Rico Debuts Second Claire’s Collection

Founder Lisette Scott was inspired by the intricacy, colors, and symbolism of African art and architecture.

Rapaport logo
SourcingFeb 21, 2024
Rapaport to Hold Another Natural Pearl Auction

Viewings start this week in New York and bidding will close on March 8.

National Jeweler columnist Peter Smith
ColumnistsFeb 20, 2024
Squirrel Spotting: Life After Rolex

Peter Smith shares advice from independent jewelers who used losing this cornerstone brand as a catalyst for reinvention.

Neile Adams McQueen and Steve McQueen
AuctionsFeb 20, 2024
Jewels from Neile Adams McQueen Shine at Bonhams

All 13 lots belonging to the actress and first wife of Steve McQueen sold at the recent “California Jewels” sale.

Stuller bench jeweler
Events & AwardsFeb 20, 2024
Stuller to Host Bench Jeweler Workshop in March

Registration is also open for its “Battle of the Benches” challenge.

Mary Ball Gorman of Henry B. Ball Jewelers
IndependentsFeb 16, 2024
Mary Ball Gorman of Henry B. Ball Jewelers Dies at 99

Gorman was an industry trailblazer, serving as the first female treasurer of Jewelers of America.

Jade Ruzzo gold and diamond Tennessee Torque necklace
CollectionsFeb 16, 2024
Piece of the Week: Jade Ruzzo’s Tribute to Tennessee

The movement of the 18-karat gold and diamond “Tennessee Torque” necklace is subtle.

Jared Goff and Claudia Cividino
MajorsFeb 15, 2024
Detroit Lions’ QB Jared Goff Going to Jared

Goff, whose fans hold up “He Went to Jared” signs at games, has signed a partnership with the retailer.

De Beers Venetia diamond mine
SourcingFeb 15, 2024
De Beers’ Production Down 8% in 2023

The company recovered 31.9 million carats of diamonds in 2023, compared with 34.6 million in 2022.

Gina D’Onofrio Heritage Auctions
AuctionsFeb 15, 2024
Heritage Auctions Names New Co-Director of Fine Jewelry

Industry veteran Gina D’Onofrio has rejoined the auction house.

Indian Diamond and Colorstone Association (IDCA) awards
Events & AwardsFeb 15, 2024
IDCA Hands Out Awards in Tucson

The association also celebrated its 40th anniversary.

A selection of engagement rings
TrendsFeb 14, 2024
5 Engagement Ring Trends for 2024

From three-stone rings to fancy shapes, experts weigh in on what consumers could be looking for this year.

Boucheron Power of Couture
CollectionsFeb 14, 2024
Boucheron’s New High Jewelry Collection Pays Homage to Ceremony, History

“Power of Couture” recalls Frédéric Boucheron’s love of fabric using diamonds and rock crystal.

Rough diamonds from Gahcho Kue diamond mine
SourcingFeb 14, 2024
De Beers’ Rough Diamond Sales Improve Slightly

The diamond miner and marketer said “solid” holiday sales in the U.S. helped stabilize the industry.

Jonker I Diamonds
SourcingFeb 14, 2024
‘100 Carats’ Exhibition Opens at LA Museum

A new display at the Natural History Museum of Los Angeles County features dozens of gemstones each weighing 100 carats or more.

Grand Seiko New York City flagship
WatchesFeb 14, 2024
See Inside Grand Seiko’s New NYC Flagship

Located on Madison Avenue, the store is its largest in the world.

GIA logo
GradingFeb 14, 2024
GIA Offering Discounts on Jade Reports

The 20 percent off promotion will run through March 31.

KIL Promotions NYC Spring Jewelry and Object Show
Events & AwardsFeb 14, 2024
KIL NYC Show Returns for Spring Edition

Its second trade event will feature vintage pieces and contemporary collections.

Lydia Courteille Lips ring
TrendsFeb 13, 2024
Amanda’s Style File: Symbols of Love

When it comes to Valentine’s Day jewels, the fun doesn’t stop at hearts.

×

This site uses cookies to give you the best online experience. By continuing to use & browse this site, we assume you agree to our Privacy Policy