Jewelry Blog

Complete Buying Guide for Blue Diamonds

13091 Customer Looking at Aquamarine Ring at EDJ Showroom in New York

Most people often conjure up images of pure, white diamonds when thinking of an engagement ring. While colorless diamonds are exceptionally valuable and elegant, color diamonds are even more sought after. Moreover, they fall into the fancy category, often even referred to as fancy color diamonds. Here’s everything that you need to know if you’re interested in buying a blue diamond ring.

Color diamonds take first place because of their extreme rarity. In fact, they can only be found in diamond mines in South Africa, India, and Australia. Furthermore, according to GIA (the Gemological Institute of America), among 10,000 diamonds, only one belongs in the fancy color category.

What Is a Blue Diamond?

Blue Diamond Engagement Ring

A blue diamond is a fancy color diamond that contains similar inherent properties to other diamonds, along with a stunning blue hue. Blue diamonds can contain different undertones, such as violet, gray, and green. 

It’s quite a challenge to find natural-color blue diamonds, as they are one of the rarest types of gemstones. The most important factors in determining the value of a blue diamond are color intensity and purity. While light-blue diamonds are the most common among blue diamonds, those with the highest color intensity are nearly impossible to find. 

As opposed to colorless and light-yellow diamonds, which are graded according to the GIA D-Z scale, fancy color diamonds are classified according to an entirely different color-grading system. The most valuable blue diamonds belong in the IF (Internally Flawless) category, while there is still no record of a blue diamond in the F (Flawless) category. 

All diamonds can be divided into five categories: Type Ia, Type Ib, Type 1aB, Type IIa, and Type IIb. 

Blue diamonds belong to the Type IIb category, which comprises approximately 0.1% of all diamonds. Apart from being extremely rare, these diamonds contain boron impurities – the reason why they exhibit intense colors in the first place. 

How Is a Blue Diamond Made? 

Diamond Mine

All diamonds are formed deep within the Earth’s crust in a complex crystalizing process that takes billions of years. In fact, all diamonds are created in this subterranean environment where concentrated pressure alters the molecular structure of carbon. Carbon is then transformed into diamonds under extreme pressure and temperatures exceeding 2,700 degrees Fahrenheit. That’s why diamonds can be found between 150 and 200km under the Earth’s surface. 

Blue diamonds, in particular, are very challenging to find. According to GIA, IIb Type diamonds are otherwise known as “superdeep” diamonds, since they are located even deeper within the Earth’s surface than other types of diamonds. 

The vast majority of blue diamonds were found in South America, while some of the most well-known blue diamond mines include the Cullinan Mine in South Africa, the Argyle mine in Australia, and the Golconda in India. 

As mentioned, blue diamonds get their blue hue from boron – a chemical element that absorbs red, yellow, and green light. Approximately only 0.001% of the Earth’s crust contains boron. This is why blue diamonds are such a rare commodity. Apart from boron, blue diamonds can also contain hydrogen, which generates gray and sometimes violet undertones. If a blue diamond has green or yellow hues, it contains traces of nitrogen as well. 

Understanding the 4Cs of Blue Diamonds 

Blue Diamond Ring with diamonds on Sides from Estate Diamond Jewelry

A diamond’s quality is measured according to the four Cs – color, clarity, cut, and carat. These metrics ultimately determine the diamond’s value and price. If you are ever considering purchasing a diamond, you should always first inspect the diamond’s four Cs before making any major decisions. 

Regarding fancy color diamonds, the most significant quality is color. This makes sense, since their colored hues are what make them so unique. Other aspects of the four Cs always take second place, but this doesn’t mean that they should be disregarded. 


As mentioned, the value of a blue diamond is mainly determined based on color saturation. Even the slightest differences in color intensity make a huge difference in value. Blue diamonds can have gray, violet, and green undertones. 

The value of white diamonds and diamonds with a slight yellow hue decreases as their color becomes more intense. On the other hand, blue diamonds with strong color intensity levels are considered more valuable. Therefore, the more saturated the color of the blue diamond, the higher the price. 


This aspect of the four Cs can also make a difference, as the size and shape of a diamond can have a huge impact on the diamond’s color. Light can be reflected more prominently on a diamond with larger dimensions. 

The shape of colorless diamonds is usually intended to intensify the sparkle and brilliance of the diamond. Interestingly, that’s not the case with fancy color diamonds, where larger cuts are used to make the color more intense. 


In terms of clarity, colorless diamonds and fancy color diamonds are both supposed to have high levels of clarity. The clearer the diamond, the greater value. Even though clarity isn’t as essential as color and cut, it’s still a valuable aspect. 


The carat aspect refers to the weight of the diamond. Since blue diamonds should be larger than colorless stones, they should reflect color better. 

Intensity Levels of Blue Diamonds 

Colored Diamond Guide Radiant Cut Square Diamonds Color Wheel

Blue diamonds contain different color intensity levels. This is how they are categorized: 

  1. Faint Blue 
  2. Very Light Blue 
  3. Light Blue 
  4. Fancy Light Blue 
  5. Fancy Blue
  6. (F) Fancy Intense Blue 
  7. Fancy Dark Blue 
  8. (F) Fancy Deep Blue 
  9. Fancy Vivid Blue 

Each of these intensity levels is stunning and beautiful, not to mention rare. However, in the case of blue diamonds, the more intense a color is, the more valuable the diamond is. If the stone appears too light, then its value might drop. Blue diamonds that belong to the fancy categories (from light blue to vivid blue) are qualified as the rarest and valuable. 

The color tone of the blue diamond is also a factor that should be taken into consideration. If the diamond’s primary hue is light blue, the color of the diamond won’t be vivid. Similarly, if the stone is too dark, then it might seem more black than blue. It’s generally advised to choose a blue diamond that is somewhere in between. 

Understanding Secondary Hues of Blue Diamonds 

For a blue diamond to be truly valuable, it doesn’t only need high levels of color saturation, but purity as well. In other words, the diamond should only feature blue hues. However, finding a blue diamond without secondary hues is nearly impossible. Almost all blue diamonds have some level of secondary hue, whether it’s a green, gray, or violet undertone. It’s also possible to find a blue diamond with a slight violet undertone, but those types of blue diamonds are rare as well. 

The most common secondary hues of blue diamonds are green and gray. Even a slight undertone can change the overall value of a blue diamond. If the green and gray hues are too intense and affect the primary blue hue, it could heavily influence the price of the diamond. 

It all boils down to personal preference, as the green and gray undertones can create a unique combination that can be elegant as well. 

Prices of Blue Diamonds 

Blue diamonds are one of the priciest fancy color diamonds, alongside red and pink. The price of a diamond most commonly depends on the four Cs – color, cut, clarity, and carat. Blue diamonds are no different. A blue diamond with the highest intensity and purity level will cost much more than a light blue diamond with a secondary hue. 

It’s challenging to come by high carat blue diamonds that don’t cost a fortune. For example, a light blue diamond with 0.3 carats usually costs $15,700. If you are looking to purchase blue diamonds that belong to the deep blue or vivid blue category, they cost $75,000 for the same carat weight. If you want a diamond with a secondary hue, they are usually much more affordable. 

The most expensive blue diamonds are usually sold at auctions. The most famous and expensive blue diamond is the Hope Diamond, at a hefty $250 million. 

Alternatives for Blue Diamonds 

If you are on a budget, or if you simply don’t want to purchase a blue diamond, there are some wonderful alternatives you can choose for your engagement ring, instead of a blue diamond ring. Here are some options to consider.


Art Deco Sapphire Engagement Ring with Diamond Halo

Due to its royal blue color, sapphire is an ideal alternative to a blue diamond. Like their diamond siblings, they are also extremely durable. Rare types of sapphires can change their hue under different lighting. For example, under fluorescent light, they exhibit a royal blue hue, and under incandescent light, they change to purple. 

Apart from the royal blue hue, they also come in green, violet, purple, orange, yellow, pink, and similar colors. You can even find black, brown, or gray sapphires, but they are much rarer. It goes without saying that sapphire engagement rings are much more affordable than blue diamond engagement rings. 

Green Diamonds 

Green Diamond Engagement Ring

If you don’t want a blue diamond engagement ring, there are plenty of other fancy color diamonds to choose from. A stunning and unique alternative to blue diamonds is green diamonds. They are equally rare, but just as beautiful as blue diamonds. 

There are different hues of green diamonds (faint green, very light green, light green, fancy light green, fancy green, fancy intense, fancy vivid, and fancy deep) to choose from. Due to their rarity, green diamonds tend to be even more expensive than blue diamonds. Therefore, if you are on a budget, perhaps this isn’t the right option for you. 


Blue Topaz Gold Ring
Blue Topaz is also the birthstone of December. Click here to purchase this ring.

While a topaz usually has a brown, orange, or yellow hue, it’s possible to find topaz engagement rings that are blue, green, purple, pink, and so on. They are much more affordable compared to diamonds, so if you are on a budget, then consider purchasing a topaz engagement ring. Just like sapphires, a topaz can display various colors under different lighting. 

While you can find a blue-colored topaz on the market, it is most commonly the result of diamond treatment. Blue-colored topazes do exist; they are just extremely rare. Therefore, if you are looking for a blue diamond alternative, then perhaps this is the right option for you. 


aquamarine halo ring

Aquamarine is a light blue semi-precious gemstone that makes a wonderful blue diamond alternative. Since they have very high levels of clarity, they are quite elegant. Aquamarines can also be transparent with light blue or green undertones, but their preferred color is moderately strong dark blue. 

They also carry a very special symbol – they are said to bring good luck and happiness to marriages.

Shopping Tips for Blue Diamonds 

Sapphire Floral Ring with Loupe

If you are in the market for a blue diamond, there are a couple of factors you need to consider. The last thing you want is to get scammed, which happens more than you think. Before you buy an engagement ring, make sure you go through this list: 

Find a Blue Diamond Expert 

If you know next to nothing about diamonds, perhaps you should consider finding an expert in this field, for example, the gemologists at EDJ. You can schedule an appointment here. EDJ specialists would be more than happy to help you out find the perfect blue diamond engagement ring for your significant other or answer any questions you might have. 

Look Out for the Four Cs 

As mentioned before, the quality of a blue diamond is determined according to the four Cs. If you aren’t sure what exactly to look for, do your own research, ask a diamond expert at EDJ, or simply go through our complete buying guide for blue diamonds. 

Think About What Suits Your Fiancée Best 

When you familiarize yourself with the four Cs, think about each quality factor at a time. What kind of diamond shape would flatter your beloved best? How many carats should it have? Should the blue diamond have low or high saturation levels? Preparing all of these questions ahead can help speed up the shopping process. 

Compare Diamonds With Similar Quality 

It’s always good to have lots of options when shopping for an engagement ring. Fortunately, Estate Diamond Jewelry offers a wide selection of blue diamond engagement rings. You can browse through our top offers right here. You will surely find something that catches your eye and meets all your requirements. 

Verify the Diamond’s Certificate 

It’s very important to choose a diamond that is either certified by GIA or AGS. This step is crucial if you don’t want to overpay for your blue diamond. At EDJ, you can rest assured. All of our diamonds are high-quality. If you are interested in learning more, you can go through our ethical guarantee here

Famous Blue Diamonds

The Hope Diamond

Blue diamonds have a long and rich history, and numerous blue diamonds have caught the public’s eye. Here are some of the most famous and expensive blue diamonds found in history: 

The Hope Diamond

Not only is the Hope Diamond the most famous blue diamond in the world, but it’s also one of the most legendary jewels worldwide. With astonishing 45.52 carats, the Hope Diamond has a fancy dark grayish-blue hue. Its current home is the Smithsonian. 

The Heart of Eternity 

This beautiful blue diamond, which has 27.64 carats, is worth $80 million. It has a fancy vivid blue hue, and it’s in a shape of a heart. Found in South Africa, in the Premier Diamond Mine. It has since been an essential piece of collections and exhibitions. 

The Imperial Blue 

This breathtaking diamond is the largest fancy deep blue diamond in the world. It has 39.31 carats, and its worth is estimated at around $79 million. It has an internally flawless (IF) clarity grade, and it’s pear-shaped. 

Find the Blue Diamond That Is Worthy 

Afshin and Adira with Vintage Earring in Estate Diamond Jewelry Box

Blue diamonds are exceptionally mesmerizing and extremely rare. If you have made up your mind about purchasing a blue diamond engagement ring, then make sure that it has the perfect color intensity, purity, shape, and size. Perhaps most importantly, make sure to pick an engagement ring that your significant other will love and cherish. 

At Estate Diamond Jewelry, each diamond ring tells a story. We hope that our complete buying guide for blue diamonds was helpful and that you could find what you were looking for.

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About Afshin Shaddaie

Afshin moved to New York City in the 1980s, and a few years later, he began his career in the fine and rare jewelry scene. He teamed up with Michael Khordipour, and they've been curating vintage jewelry ever since. He also regularly contributes to Forbes, Rapaport, CNBC, The Knot, and Insider. Afshin constantly travels to international shows and private viewing events in the hope of finding rare vintage rings that will be important enough to make an impression. He is available for appointments at our New York showroom when he's not traveling. In 2019, Afshin authored his book called The Engagement Ring Guide for Men. He is considered one of the world's foremost authorities on vintage jewelry and antique diamonds. His favorite jewelry era is Art Nouveau, and he loves rare Italian jewelry from the 1950s - 1970s. The Natural Saltwater Pearl is his favorite precious jewel.