CLEARANCE SALE | GET UP TO 80% OFF CLEARANCE

GET UP TO 80% OFF CLEARANCE

SHOP NOW*T&Cs Apply

Learning Library

Andesine Gemstone

Sometimes heated and treated, but always a gem that captures the imagination of all true collectors and connoisseurs.


What an interesting world we live in! I have always explained to my jewellery team that you should never state anything about gemstones as an absolute fact and instead should use phrases such as ‘currently one of the rarest gemstones on the planet’ or ‘sources inform us that the gem will no longer be mined within the next 10 years’.Remember they used to say Garnet comes in every single colour apart from blue, but then what did they discover in Madagsascar in 1998? You guessed it!

It’s so easy to get carried away in an industry where people state things as fact, but in reality this industry should by now, after trading coloured gemstones for over 5,000 years, have begun to realise that Mother Nature is never predictable and often seems to do things that make even the world’s best gem experts occasionally look a little silly.

In 2002 at the world famous Tucson Gem Show in Arizona, when a stunning new gemstone called Andesine exploded on to the scene (well, it wasn’t brand new, but we will come to that in a moment), there were many stories and myths surrounding its original location and what in fact the gemstone was.

The gemstone is so stunning that the miners of this new source kept its location a real secret and many in the industry incorrectly said that it came from either India or the Democratic Republic of Congo. With so much demand for top quality Andesine, many in the industry were selling very similar pieces and claiming it was from the same source as the very finest material, and as nobody knew exactly where the new source was, nobody could dispute the dealers’ claims of origin. Whilst many were uncertain of the location of this new magnificent gemstone, it was certainly being mined somewhere in the Himalayas, a far cry from where it was originally discovered in the 1840s in the Andes Mountains in Bolivia, from where its name is derived.

But what is this gemstone and what is its real name?! Unfortunately, this is still a matter for debate. Firstly a fact: the gemstone is a top quality red gemstone and is a member of the Feldspar family. The finest examples are right up there with Paraiba Tourmaline and Alexandrite. In fact, Andesine shares similarities with both in that there is also a green colour change version of the gemstone which appears very similar to Alexandrite and like Paraiba, part of its magical brilliance is due to the presence of Copper.

At the 2008 Olympic Games held in Beijing, there was a large display featuring many pieces of Red Andesine which had been chosen as the official gemstone of the games. This raised alarm bells in the industry, as it was believed that very little of the gem had ever been discovered in China and Tibet.

On the 31st of January 2011 at the Gemstone Industry Laboratory Conference (the GILC is the most important meeting in the gem trade calendar relating to the technical aspects of our industry), the forty or so delegates spent two hours discussing a recent trip to the Andesine mines of Tibet by several respected members of the trade. Here, we were informed that the group had travelled to the highlands of the Himalayas in Southern Tibet to the Bainang County, which is located some 45 miles south of Tibet’s second largest city, Xigaze.  The road from the city is nothing more than a dirt track and the group had to ascend to 4000 metres above sea level. In the winter the track is impossible to travel as it is deep under snow and even when the team arrived during the summer they said the air was frigid and very thin due to the altitude.

At the remote area where the mines are located, several families have now set up home. During the time spent in the area, the team did indeed uncover some pieces of natural Red Andesine themselves, but only saw around 10 gem miners in the whole region. The fact that there were so few miners in this remote location led the team to believe that although they had proven that Red Andesine can be found naturally in Tibet, it could not be the only source of the gem. So where is the majority of Red Andesine being unearthed? The answer lies in Inner Mongolia. This is a country that is landlocked: to its north is Russia and to the east, south and west is China. In terms of geographical size, the country is the 19th largest country in the world spanning a huge 604,000 square miles, yet its population is only 2.9 million. That’s the equivalent of the population of Birmingham being spread across a country six times bigger than Great Britain. To the north of the city of Baotou is the small county of Guyang: here in the small villages of Shuiquan and Haibouzi for many years local miners have been excavating small quantities of fine yellow Andesine (some call it Yellow Labradorite as both are plagioclase Feldspars). Since 2003, the main mine just outside of the village has been run by Wang Gou Ping. At the end of each year’s harvest, Wang hires 40 or so farmers to mine for the treasured Yellow Andesine. Many of these golden glowing gems are then treated with diffusion and then turn orangeish red, looking very similar to those coming out of Tibet. What are the main differences between Andesine coming from these very different locations, other than one is colour enhanced? As they say in the wine trade, the ‘terroir’ is very different, a term which expresses the particular characteristic bestowed by the geographical, geological and climate conditions. In Tibet the gems are mined at 4000 metres above sea level, whereas in Mongolia the landscape is very flat. In terms of chemical composition, the gems from Tibet have a lower Ba/Li ratio than those discovered in Mongolia, but have a natural presence of copper.

The conclusion reached from the dedicated work of the team that went to both Tibet and Mongolia in 2010, is that their natural Red Andesine is being mined in Tibet, but the quantities are extremely small. The vast majority of Red Andesine on the market we now believe to have come from Mongolia and has had its colour transformed from a sunflower yellow to a beautiful orangish red colour through diffusion. When it comes to Green Andesine and Colour Change Andesine, these are incredibly rare and beautiful gems also. The colour change variety has some of the best colour change we have ever seen in a gemstone, having the ability to go from a stunning bottle green colour under florescent lighting, to a glorious almost Amethyst purple colour under a strong torch light.

I received a letter from a lovely customer who had taken her jewellery to be valued and on return was delighted that it had come back at £5000. She was told that the gem was not a Green Andesine but actually an Alexandrite! However, when I was able to examine the piece, I discovered the piece was in fact Andesine and the jeweller had made a basic mistake. Firstly, the two gems look visually different and their refractive indexes are also miles apart! What I always suggest is that when you purchase a rare gemstone, if you want to have it properly valued, you will need to go to an expert in coloured gemstones!

 

Back to Learning Library

 

 

 

 

 

Colour change Andesine is almost

impossible to obtain.