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Tourmaline
Tourmalines have a variety of exciting colors with one of the widest color ranges of any gem.
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“Paraíba”-Type Copper-Bearing Tourmaline from Brazil, Nigeria, and Mozambique: Chemical Fingerprinting By LA-ICP-MS
Gem-quality bright blue to green “Paraíba”-type Cu-bearing tourmaline is now known from deposits in Africa (Nigeria and Mozambique), in addition to three commercial localities in Brazil (in Paraíba and Rio Grande do Norte States).
Geographic Origin Determination of Paraíba Tourmaline
Copper-bearing gem tourmaline, known as Paraíba tourmaline after the location of its original discovery, is prized for its vivid blue to green color. This article explains GIA’s use of quantitative chemical analyses to distinguish samples from Brazil, Nigeria, and Mozambique.
Micro-Features of Tourmaline
Provides a visual guide to the internal features of tourmaline as well as tourmaline inclusions in other gem hosts.
Brazilian Watermelon Tourmaline with Iris Effect
A pair of watermelon tourmaline slices from the Cruzeiro mine displays a rainbow of colors.
Interesting Metallic Platelets in a Brazilian Paraíba Tourmaline
Microscopic observation unveils the first known instance of skeletal metallic inclusions in Brazilian Paraíba tourmaline.
Cat’s-Eye Paraíba Tourmaline with Copper Inclusions
The Tokyo laboratory examines a Paraíba tourmaline with chatoyancy caused by copper inclusions.
Book Review: Pegmatites and Their Gem Minerals
Review of Pegmatites and Their Gem Minerals, by Michael Menzies and Jeffrey Scovil.
The Big Find: Celebrating 50 Years of Maine Tourmaline
The historic discovery of a Maine tourmaline source is celebrated through jewelry designs featuring gems unearthed 50 years ago.
Namak Mandi: A Pioneering Gemstone Market in Pakistan
Documents Namak Mandi’s transformation from a salt market to one of Pakistan’s primary gem trading centers, with a look at the commercial activities taking place today.
The Geographic Origin Dilemma
An overview of the geographic origin complexities facing the gem and jewelry industry today.
Field Gemology: Building a Research Collection and Understanding the Development of Gem Deposits
With more than 90 field expeditions on six continents since 2008, GIA has accumulated over 22,000 colored stone reference samples. This extensive collection of colored stones with known origins supports GIA’s research on geographic origin determination.
Emerald: The Superstar of Trapiche Gemstones
Trapiche emeralds, which display a distinct six-spoke wheel pattern, set the standard as some of the finest and most spectacular crystals unearthed.
