Seek the World’s Most Vivid Blue Spinel with GIA Field Gemmologists
October 6, 2016
In this new video from GIA’s field gemmology department, you will accompany field gemmologist Vincent Pardieu to Vietnam’s striking limestone mountains in search of sky-blue spinel.
Although miners recover blue spinel in Sri Lanka, Tanzania, Myanmar and Pakistan, Vietnam’s Luc Yen district is a leading source of the most vividly blue gems. The best of them have the same luminous quality as Paraíba tourmaline. “The blue spinel you have in Vietnam has really no equivalent,” explains Pardieu. “The top-quality blue spinel from Vietnam is really the top-quality blue spinel in the world, in my opinion.”
Luc Yen district is located in Yen Bai province, in Vietnam’s scenic north. It’s a vivid patchwork of steep-sided, jungle-covered karsts separated by narrow valleys filled with paddy fields and villages. Luc Yen’s capital, Yen The (confusingly also known as Luc Yen), is about a six-hour drive, 250 km (155 miles) from Hanoi. All of the district’s blue spinel mining sites are within 20 km (12 miles) of the town.
The GIA team starts off in Luc Yen’s bustling gemstone market. Before the 1990s discovery of Vietnamese ruby, Luc Yen was little known—a small agricultural backwater. The town grew rapidly after gems were discovered in the surrounding mountains and streams. Luc Yen’s first gem market opened in 1987, and today this once impoverished town is northern Vietnam’s busiest gem-trading centre.
At the market, gems from the area’s mountains and fields—rough spinel octahedra, faceted spinels and cabochons—lie in rows on dealers’ little wooden tables. “Visiting the market here is quite an experience for anybody,” says gemmologist Manny Diaz. Beautiful cobalt-blue spinels are present at many of the tables. “Material like this is really incredibly rare on the surface of the earth,” says Pardieu. He explains that visiting the local gem market is an excellent way to assess the availability of different materials. It also gives gemmologists a way to assess current gem production in the local mining areas.
It takes several hours to reach the blue spinel mines. The GIA team travels by motorcycle from the town to the countryside. Once there, they must make the trek up into a forbidding karst landscape to reach the mines. Luc Yen’s rugged limestone mountains formed when rainfall dissolved the limestone and created underground drainage systems, sinkholes and caves. These features make it challenging to reach the mines, where ruby, sapphire and spinel are recovered from primary and secondary deposits using artisanal methods. “If you want to go to see the primary mines that are producing this sky blue spinel, there is no other way,” remarks Pardieu. “You have to face the karst and go up in the mountain.”
This means hours of steep ascent, navigating the sharp ridges and deep crevices that make up the face of the mountain. “There is a crevice about 4 to 5 metres deep, full of wood and sharp marble pinnacles,” observes Pardieu, “so you don’t want to fall in there!”
“For the past ten minutes, we have been climbing the Cung Troi cliff, which is the main spinel mining area here,” explains Pardieu. “Cung Troi is a very special place, as this is the place that has produced most of the spinel crystals in matrix for the past 20 years.” Cung Troi—which means “Sky Gate”—is a source of pink-to-purple spinel, which occurs in marble along with minerals like pargasite. The spinels range in size from just a few millimetres to over five centimetres, and are of octahedral habit. Crystals in matrix are often carved into decorative shapes, which are highly valued due to the strong domestic market for items related to phong thuy—the Vietnamese version of feng shui.
As the team nears the Cung Troi spinel mine, they clamber up steep slopes strewn with angular blocks and tailings of white marble. Standing in front of a marble cliff, gemmologist Manny Diaz examines one half of a drill hole in a split rock face. “They’ll drill and they’ll pack that hole with an explosive…Once it falls, they’ll come down, out to the blast site and they’ll start picking up all the rubble,” he says. Miners attack the rubble with sledgehammers to look for spinel crystals, which stand out like glowing embers against the snowy white marble.
When the team joins the miners in their hut for a meal, Pardieu explains Cung Troi’s geology: “It seems that you have three parallel veins…one with pink spinel, one with blue spinel and one with ruby,” he says.
Later, they watch as some miners struggle to move a huge marble block down a steep slope of angular, boulder-size tailings. “We just witnessed the team of miners that we spent the day with on the cliff, taking down a huge piece of marble that they collected from the top,” Pardieu observes. “Inside, we can see there is some pargasite, there is also some spinel. They’ll probably sell it to a carver and the carver will slowly take out the marble in order to reveal the spinel and the pargasite, which are hidden inside.” The heavy boulder tugs the miners downhill. They laugh, but they’re only barely in control.
Next, the team reaches the Bai Son blue spinel mine—the main objective of the expedition. The primary deposit at Bai Son is located on a 600-metre high (1,970 foot) marble mountain. Local miners—mostly farmers—extract the spinel from the marble using hand tools and jackhammers. “Here we are on the blue spinel vein,” remarks Pardieu. “This is a most famous spot for blue spinel of the sky-blue quality.” Although blue spinel is found in the white marble at Bai Son, the crystals are usually of low transparency. Gems weathered out of the marble are also found in crevasses at Bai Son, and in places where miners follow the caves underground.
Pardieu sums up the rationale for this and all the other field expeditions he conducts for GIA: “I travel to gem-mining areas around the world and I collect samples. So we need to have a reference sample from this area in order to be able to identify the stones that were mined in the past, that are mined today, and will be mined in the future.”
This GIA Field Expedition (FE65) took place in 2015. Besides Pardieu, the participants were video cameramen Didier Barriere-Doleac and Didier Gruel, and expedition members Manny Diaz, Philippe Labrot, Lucie Martinez, Lauriane Pinsault and Wim Vertriest.
GIA staff often visit mines, manufacturers, retailers and others in the gem and jewellery industry for research purposes and to gain insight into the marketplace. GIA appreciates the access and information provided during these visits. These visits and any resulting articles or publications should not be taken or used as endorsements.