>> This is thought to be the biggest blue topaz in the world. Described as flawless and priceless. Unearthed by a man likened to Indiana Jones and soon, to be on display at London's Natural History Museum. I'm Reuter's reporter, Mia Wombsley at Austrian Minerals in central London. This precious stone has been kept in vaults for three decades.
Since it was discovered in the Brazilian Amazon in its natural form. It weighs about as much as two bags of sugar and is 9,381 carats of exceptionally vivid blue. It was found by Max Ostro, a British explorer who braved the elements to get his hands on it, as his son explains.
>> The perils when you're in the Amazon region of water going in to the mines. Where piranha can suddenly appear very quickly, and you have to get out. Not because of water flooding and drowning, but rather for risk to your your body. Because these things do move very quickly and they are rapacious eaters.
>> Maurice has decided it's time for his father's gem to see the light of day. But rather than put such a personal object up for auction, it will be on permanent loan to the Natural History Museum. Displayed in a bullet proof glass cabinet in the mineral section.>> I think it will tell us another bit of the natural story.
So you start off with a rough mineral, which is all kind of quite interesting and I really like that as a scientist. And then we do things to it and we'll change it, we'll cut it into something. And this is a really fantastic example of the way in which we've crafted something out of nature.
>> The museum has had to beef up its security to house the new arrival. But anyone tempted to organize a midnight heist might want to reconsider. A one of a kind piece like this would be instantly recognizable by any buyer. And dividing up the unique stone would obliterate its value.