Showing posts with label diamonds. Show all posts
Showing posts with label diamonds. Show all posts

June 30 - Excelsior Diamond Discovered

  Posted on June 30, 2022     


This is an update of my post published on June 30, 2011:




How'd you like to be a worker at a mine, just busy loading a truck with spadeful after spadeful of dirt—and then you spot the world's largest diamond? What would you do?

The African man who found the Excelsior Diamond in South Africa, on this day in 1893, hid it from his overseer and personally delivered it to the manager of the mine. The blue-white diamond weighed more than 970 carats, and news of its discovery quickly spread all over the world.

For 12 years, this was the record holder of the largest diamond ever found. However, it was supplanted as “the biggest” by the Cullinan Diamond, which was more than 3,000 carats!

The Excelsior Diamond was eventually cut into ten stones.




By the way, do you wonder what happened to the man that found the diamond? He was given a 500-pound reward plus a horse equipped with a saddle and bridle.


This diamond, Lesidi La Rosa, is a little bit larger than
the Excelsior, but I thought that the photo, which includes
adult hands holding the giant stone, gives a better idea of
the size than do all the photos of the Excelsior I saw...

Did you know...?

  • Diamonds are made of carbon, the same material that makes the graphite in our pencils and coal!


  • Diamonds are formed in high-pressure, high-temperature conditions deep underground, in the Earth's mantle.
  • Diamonds are the hardest natural material known, so they are often used in cutting and polishing tools.
  • Many diamonds are clear and colorless. Small amounts of impurities (such as one atom of the contaminant per million carbon atoms) can give a diamond color. If the contaminating atoms are boron, the diamond is blue; nitrogen atoms make a diamond look yellow, and diamonds that have been exposed to radiation can become greenish.
To see some famous diamonds, check out this website. 



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November 10 – Anniversary of a Big-Time Gift

Posted on November 10, 2018


The Hope Diamond is one of the most famous diamonds in the world. I wrote about it (or at least the earlier version of the diamond, called the "French Blue") in another post.





On this date in 1958, jeweler Harry Winston donated this large, unusually blue diamond to the Smithsonian Natural History Museum, where it can be seen by all...for free!

I want to talk about two aspects of the diamond: the science of it and the silliness of it.

The silliness

The diamond is supposed to be cursed - whoever owns it or wears it is supposed to have misfortune or tragedy. I assumed that this rumor was the result of a couple of tragic incidents that were cherry-picked without mentioning owners and wearers who were perfectly fine during and shortly after their time with the diamond. But instead there is evidence that the tragic stories were simply made up in order to create a "buzz" about the jewel, and shroud it in mystery, and therefore raise the worth of the jewel. (I would think that the rumor of a curse would lower the worth of the jewel, but apparently not!) 

The long list of people who had encountered the diamond and then were ....well, torn to pieces by a mob of people, in one case, and by a pack of wild dogs, in the other - people who were murdered, who were killed in a revolution, who committed suicide - people who died in "misery and want" or were hanged or or or ... Apparently there's no evidence that these stories, published in the New York Times, were true or even partly true!

The folks at the Smithsonian Museum have pointed out that the Hope Diamond has only brought good things to the museum, and has led to zero problems or tragedies.

The science

Diamonds are usually clear, but other colors can occur: can you imagine gray, white, blue, yellow, orange, red, green, pink, purple, brown, or black diamonds? Colored diamonds either include impurities or have structural imperfections - it is the pure and perfect diamonds that are perfectly transparent and colorless.


Diamonds are either pure carbon or mostly pure carbon, but then again, so is graphite - the dark gray stuff inside our pencils! (Coal and charcoal are mostly carbon, and they are black, but they have a lot more other sorts of atoms than do diamonds and graphite.) The difference between pure-carbon diamonds and pure-carbon graphite is the arrangement of those carbon atoms. Diamond atoms have super strong bonds, and all of the carbon atoms are in tight formations of perfect tetrahedra. Graphite atoms, on the other hand, have some strong bonds but also some looser bonds. This means that the atoms form sheets that slide apart from one another.

Left, diamond and its crystal structure.

Right, graphite and its structure.

Those structural differences lead to diamonds being really hard as well as clear, and graphite being soft as well as dark. 

Uncut blue diamond
The Hope Diamond is blue because it has boron atoms. Not many boron atoms, mind you - there is about one boron atom per a million carbon atoms in a blue diamond! And the very, very, very occasional boron atom has one fewer electron than its carbon neighbors, so it can't form the same four perfect bonds. This means that there is a bit of freed-up electrons in a blue diamond - electrons that can interact with light and give the diamond a blue color!

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August 23 – Anniversary of Cartier Founding a Town

Posted on August 23, 2014


A lot of early European explorations of the so-called New World were focused on finding a passage to the “East Indies” – a place with silks and spices to sell – or on finding gold and other treasures.

Of course, soon Europeans focused on creating settlements – new towns that would grow to become new cities and countries – in the New World.

That certainly could be a tricky proposition. After all, there were already people living in the New World. These Native Americans had more know-how about the land and the resourcefulness and, in many cases, weapons to defend their rights to that land.

Perhaps that is why Jacques Cartier, a French explorer tasked to found a permanent settlement in the New World, in what is now Canada, chose not to settle too close to Iroquois Indians.


What is recorded about Cartier's encounter with the Iroquois is that he became worried about their “show of joy.” Also, there were an awful lot of Iroquois. Cartier decided to sail upriver to found a town in an emptier spot.

And so it was that, on this date in 1541, the fortified settlement called Charlesbourg-Royal was created. The colonists and cattle aboard Cartier's ship landed after three months at sea, and they began to farm.

Cartier continued to explore, to fulfill another of his assigned tasks, to find the rich kingdom called “Saguenay.” The Kingdom of Saguenay was, according to the Iroquois, a kingdom of blond men, of gold, of furs, of treasure galore. Cartier (and later other French explorers) searched and searched for this kingdom, but they never found it; scholars are not sure if the place was just a legend that the French mistakenly took literally, or if the Iroquois were deliberately lying in order to trick the French.

However, some of Cartier's men were delighted to find diamonds and gold, and soon the ship was full of the precious substances!

When Cartier gave up the search for the Kingdom of Saguenay, he learned that the settlement he had helped to start had fallen on hard times: the Iroquois had attacked and killed about 35 French settlers, and the rest of the settlers sounded pretty miserable. Cartier knew he didn't have enough men to protect the base, so he set sale for France.

Remember, he was convinced that his ship was laden with precious diamonds and gold.

It turned out that, not only had Cartier failed to find the treasure-filled kingdom, but he had also badly misjudged the minerals his men had collected. Instead of being diamonds, the crystals were merely common quartz. Instead of being gold, the sparkling mineral was iron pyrite (also called “fool's gold,” because...yeah). For centuries later the French expression “faux comme les diamants du Canada” referred to this disappointment: “as false as Canadian diamonds.”

This photo shows the difference between pyrite (L) and gold (R).

This diagram shows one difference between
diamonds and quartz; light bent within a
quartz crystal often has rainbow colors.

(Thank goodness for the fine jewelry company of Cartier, the common expression didn't mention Cartier's name in connection with the fake diamonds!)





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