diamonds

Diamonds are a rock collector’s best friend

Lesedi La Rona Diamond Sells
hand holding largest uncut diamond from Lucara

Photo by Donald Bowers/Getty Images for Sotheby’s

In the fall of 2015, a 1,109 carat white diamond was found in the Lucara mine in South Africa. The diamond is called the Lesedi La Rona, which means “Our Light” in Setswana. They tried to sell it at a Sotheby’s auction last year (July 2016), and we even wrote about it on Show Me Rockhounds, but no bidder met the reserve. Now, it has finally sold.

On September 26, 2017, Graff Diamonds announced that they bought the Lesedi La Rona for $53 million in a private sale. The CEO of Lucara says $53 million is higher than the highest bid they got at the auction last year, but he wishes he could have got a higher price. (Don’t we all!)

What will they do with it? Lawrence Graff, the founder of Graff Diamonds, says, “The stone will tell us its story, it will dictate how it wants to be cut, and we will take the utmost care to respect its exceptional properties. … I am privileged to be given the opportunity to honor the magnificent natural beauty of the Lesedi La Rona.”

https://www.cnbc.com/2017/09/26/large-diamond-the-lesedi-la-rona-sells-for-53-million.html

World’s Largest Uncut Diamond Up for Auction
hand holding largest uncut diamond from Lucara

Photo by Donald Bowers/Getty Images for Sotheby’s

From the New York Times, June 27, 2016:

In the fall of 2015, a 1,109 carat white diamond was found in the Lucara mine in South Africa. The diamond is called the Lesedi La Rona, which means “Our Light” in Setswana. On Wednesday, June 29, 2016 it will go up for public auction at Sotheby’s in London. Usually, precious stones like these are sold secretly by sealed bids and kept anonymous, so this Sotheby’s auction is unusual. This is the first time that such a large diamond has been on sale publicly.

The Lesedi La Rona is a type IIA diamond, which is very rare and is the most chemically pure type of diamond. Other famous IIA diamonds include the Koh-i-Noor and the Cullinan, which is 3,106 carats and is the biggest diamond ever found. The Cullinan was cut into 9 different stones and the pieces are now owned by various monarchs. Sotheby’s says that “whoever buys the Lucara stone will pay Sotheby’s a 12 percent fee, known as the buyer’s premium, on the hammer price for anything over the first $3 million, and a higher percentage of the first $3 million.” Whoever buys the stone will then have to decide if they want to have it cut. What a hard decision! What would you do?

The whole article is here: http://www.nytimes.com/2016/06/28/business/worlds-largest-uncut-diamond-heads-to-auction-a-break-with-tradition.html

UPDATE: It turns out nobody bought the diamond because the bids failed to meet the minimum reserve price. The reserve price was secret (just like at eBay) but it must have been more than £45 million ($61 million) because that was the highest bid. Maybe it will go on sale again later. Source: http://www.bbc.com/news/uk-england-london-36660076

Chemical Composition of Gemstones

Here’s a neat infographic from Compound Interest (one of my favorite websites) that describes 16 different gemstones and why they have different colors. It also includes their chemical formulas and hardness on the Mohs scale.

Many gemstones would be colorless or a different color if not for the presence of small amounts of transition metals such as chromium or titanium. For example, you can see that aquamarine and emerald both have the same chemical formula Be3Al2(SiO3)6, but emeralds are green because of chromium ions replacing some of the aluminum ions and aquamarines are blue because of iron 2+ or 3+ ions replacing some of the aluminum ions. Click through to read the whole article, because there are many other ways that gems and minerals get their colors!