If I were to answer with one or two words, the answer would be similar to that of a lawyer or an accountant – “It depends!”
The rarity of blue diamonds will depend on the spectrum of diamonds variety we are talking about, i.e. whether we are referring to all of the diamond colors or are narrowing our question to a select few. If we are talking about the full spectrum of diamonds, including colorless and the full spectrum of fancy color diamonds (which includes 12 or 14 colors, it all depends who you ask), then the answer would obviously be yes.

Blue Diamonds Are Rare – Why?

On a yearly basis, there are anywhere between 120 million to 140 million carats of rough diamonds that are unearthed around the world; from Russia to Canada to Brazil to Australia and Africa. Statistically, only 20% of that quantity are considered gem quality, meaning that the majority, or 80% are used for industrial purpose. This means that only between 24 million to 28 million carats of rough are gem quality. This establishes the rarity of diamonds overall. Another statistic, states that on average there is a 40-60% loss of the rough as polishers polish the diamonds. Let’s take the average and say 50%, therefore only between 12-14 million carats of polished diamonds will be produced yearly – and that just made our overall quantity even smaller. According to the GIA, Fancy color diamonds make up only 0.01% of that. That means that just 120,000 to 140,000 carats will be considered fancy color diamonds. The vast majority (80%) will be Brown and Yellow Diamonds. Another significant portion will be black and grey. About 80% will have a secondary color or even a tertiary color, also known as modifying colors. This leaves us with approximately 4% to be shared between pink, blue, red, orange, green, purple and violet Hues. This translates to 4,800 to 5,600 carats in total, or about 0.004% of all total diamonds mined annually. Would you consider it rare? I would.

Visual representation of the rarity of blue diamonds within the diamond market and within fancy color diamonds

At What Point Does Anything Become Rare?

Within these 5,200 carats, we now need to divide the diamonds within the 9 depths of color in which they are classified: very light, light, fancy light, fancy, fancy intense, fancy vivid, fancy deep, and fancy dark. There are literally a handful of people who would know how many will be classified into each, and that is only once each diamond is certified. The majority of diamonds are certified by the leading global lab; the Gemological Institute of America, also known as the GIA.

From a recent GIA Monograph about the Blue Moon of Josephine, the GIA claimed that out of a random sample review of 400 blue diamonds, only 4 were classified as being Fancy Vivid Blue (the most valuable color intensity of blue diamonds). Since November 1999, only 50 Fancy Vivid Blue diamonds have ever been sold at auction. This includes Sotheby’s, Christie’s and Bonham’s, the leading three auction houses worldwide. Guess how many colorless diamonds have been Sold? You guessed it, endless… (thousands per year, going back decades!) Out of the 50 Fancy Vivid Blue diamonds, only seven were above 10 carats in size, sixteen of them were between 5 and 10 carats, sixteen were between 3 and 5 carats and eleven were between 1 and 3 carats. The blue diamond below 1 carat in size can be sold in the market more easily as they are considered “more affordable”. In short- blue diamonds are extremely rare out of all the diamonds mined annually, Fancy Vivid Blue diamonds are even more rare, and large Fancy Vivid Blue diamonds (above 5 carats) are a veritable unicorn.

The 12.03 carat Fancy Vivid Blue ‘Blue Moon of Josephine’ diamond     Image credit: Sotheby’s

Blue Diamonds Are Not Rare – Why?

If we had to compare Blue diamonds to red diamonds, then we would say that blue diamonds are not rare (to be more specific – not AS RARE). During the same 20 year span that 50 Fancy Vivid Blue diamonds have appeared at auction, 58 Fancy Intense Blue diamonds, 13 Fancy Deep Blue diamonds, 11 Fancy Blue diamonds, and 8 Fancy Light Blue diamonds also appeared at auction for a total of 140 blue diamonds. However, only 9 Fancy Red diamonds and 11 Fancy Purplish Red diamonds appeared at auction concurrently. That is 140 compared to 20, which makes Blue 7 times more available, or about 88% of the combined number of diamonds were blue, and that, statistically does not make them rare. It is quite simple to show how rare something can be, it all depends to what we compare it. If we add Green diamonds to the mix, then we can say that Green is even more rare since only 6 Fancy Intense Green, 2 Fancy Vivid Green, and a single Fancy Green appeared at auction during this time. The colors Orange, Purple and Violet are extremely rare as less of them appeared in auction than green diamonds.

The 14.62-carat Fancy Vivid Blue ‘Oppenheimer Blue’ diamond     Image credit: Christie’s

How Has the Rarity of Blue Diamonds Affected Their Value Over the Years?

Our first recorded blue diamond at auction was back in 1990, when a 1.07 carat Fancy Light Blue was sold at a Christie’s New York auction for a mere $22,600 per carat. Going forward to 2016, a 5.06 carat Fancy Light Blue diamond was sold for over $286k at a Sotheby’s New York auction, over 12 times the price!

An even more extreme case would be with Pink diamonds, where a 1 carat Fancy Intense Pink has seen a 35 fold increase in its per carat price in the last 20 years!

To conclude, we can say that blue diamonds are rare when we look at the overall bigger picture of the diamond spectrum. They are rare enough that most jewelers may never see a blue diamond in their entire career.