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Blue diamonds are one of the types that are especially rare.

If colored diamonds’ rarity can be tracked on a scale with four groups, the second most rare group will include the blue diamond type.

You’ll find pink diamonds easier than blue ones, but some types such as red diamonds, violet ones or purple shaded gems are even rarer than the blue stones.

Within the blue grouping you’ll also find stones with different color strengths.

In general, the stones become rarer the stronger their colors are.

Read up on diamonds in Eden Rachminov’s book “The Fancy Color Diamond Book” and you’ll learn that 0.1% of the diamonds classified as ‘fancy colored’ will be labled as Type IIb Blue diamonds.

Compare natural blue diamonds to Picasso paintings and you’ll find one stone for every 100 art pieces that’s up for auction.

But what lies under the surface of these stones?

They’re fascinating not only for the chemical substances inside them, but for the role they’ve played in history.

Ready for some interesting facts? We tell all.

Also read: How To Tell Good Diamonds From Bad


The Color Blue Explained

If you don’t know this yet, colored diamonds take their hues from impurities inside the stones. For blue diamonds the same scientific reason applies and for this group of colored diamonds the hue is thanks to the presence of boron.

These particles can absorb yellow, so when light shines on it, it will reflect blue.

Of course, similar to other colored diamonds, you can come across various blue hues:

  • Pale ones like clear skies

  • Steel blues

  • Intense blue like the depths of the sea

To differentiate, names representing these hues can often be found, including ‘baby’, ‘midnight’ or ‘royal’.


The Types

When you see Type IIb on a blue diamond’s grading it means you’ve got one of the most pure ones.

This means there’s no, or very few, nitrogen impurities.

Moving to Ia stones, these jewels will have secondary hues and hydrogen affects the color you’ll see.

Known as a modifying color, these will also be mentioned in a gemmological grading report of a diamond.

Examples include ‘gray-blue’. ‘Greenish-blue’ is another one.

Diamonds can also be compared based on their ability to conduct heat and electricity.

Natural blue diamonds are the only types of these stones that can do this—chemically altered color enhanced stones can’t do this either—which means you won’t find a harder conductor anywhere on earth.


Blue Diamonds: Where do They Come from?

For blue diamonds you’ll primarily turn to South Africa’s Cullinan Mine, situated near Pretoria.

The mine is owned by Petra Diamonds.

Some great discoveries have taken place on this mine, such as a blue diamond with a $25 million price tag.

This 29.6 carat stone was sold in the rough for that high amount, then polished and given the name ‘blue moon’ when it became a 12 carat vivid blue stone.

Or perhaps you’ve heard of the biggest blue diamond discovered to date? At 122.52 carat, it was quite the find.

Other locations known to produce blue diamonds is India’s Golconda mine and Lesotho’s Lesteng mine.

If you’re looking for a blue diamond that fluoresce you’ll need to travel to Zimbabwe because the NCDIA note that this is the only place you’ll see this phenomenon.

After finding a diamond it must be polished and NCDIA notes Israel as the best for this task.

Particularly for jewels 3 carats or less, you should use this market for manufacturing.

If a gem weighs more than that, New York and Antwerp are the best places to consider.


How Valuable are Blue Diamonds?

Their rarity combined with a high demand makes blue diamonds valuable and expensive.

They also become pricier over time, with the NCDIA reporting a 12% to 17% yearly price increase during the last 10 years.

No matter how saturated the market gets, blue diamonds become more valuable all the time.

Yes, the vivid blue stones are more in demand, but even lighter hues of blue still fetch astounding prices.

As much as $1 million—sometimes more—per carat for vivid blue jewels of over 3 carats in weight, although cut, clarity and the weight also determine the worth.

At auctions the prices keep breaking records, bought as collectors’ items or by investors aiming to capitalize.

With only two to four noteworthy blue diamonds entering the market each year, it’s clear that sales related to blue diamonds are quite a novelty.


A Few Blue Diamonds of Note

You can’t mention blue diamonds without talking about the Hope Diamond.

It’s the most famous blue stone, but possibly also the most noteworthy diamond on the globe.

With a weight of 45.52 carats and a grayish-blue hue, there’s a remarkable history to it and some even think it cursed because of deaths related to it.

You’ll find it at the Smithsonian Natural History Museum thanks to well known jeweller Harry Winston who bought it and donated it within a day.

Perhaps you’ve heard about the Star of Josephine?

This is a vivid blue stone at 7.0 carats which was discovered in 2008. It contains no flaws inside and was sold for $9.49 million a year after it was found.

That earned this cushion-cut diamond a world record of all gemstones: the highest cost per carat ever sold at an auction.

Except for the Hope Diamond, with a weight of 42.92 carats the Tereschenko diamond is the biggest fancy blue stone on the globe.

And let’s not forget the Wittelsbach-Graff: a blue diamond found mid-1600s.

Laurence Graff purchased it and recut it as well as polished it.

This resulted in a weight of 31.06 carats. It was sold in 2011 for $24.3 million.

In recent years Petra sold a 29.6 carat blue diamond—rough—for $25,6 million.

That means it cost the buyer almost $1 million for each carat.

And in 2014 Harry Winston purchased a stone called the Perfect Blue for $24.24.

This one had no internal flaws and was pear shaped; a vivid blue color.

The new owner gave it a new name, the ‘Winston Blue’.

There’s no question that this rare type of stone resulted in remarkable stories in the past.

What more will happen in future?

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