What Makes a Diamond Rare?

From 11th century Arabian merchants to the latest flash of Hollywood bling on the red carpet, rare diamonds have always captured our imagination. But what exactly makes a diamond rare?

What makes a diamond rare?
What makes a diamond rare?

While we often hear about bigger and bigger diamonds valued at higher and higher prices each year, there are many other qualities beyond size that make a diamond rare and valuable.

  • Carat – While the value of a diamond goes up as the carat or weight increases, the size of the diamond can greatly affect its rarity. Large diamonds are more rare than small diamonds, so a larger stone doesn’t just cost more; it also costs more per carat.


  • Only about 1 in 1 million diamonds mined are quality one-carat stones, only 1 in 5 million are 2-carat; and 1 in 15 million are 3-carat.


  • Looks can be deceiving: If there are two D-color round brilliants with identical clarity and cut, that are close in carat weight, the one that appears larger, but actually weighs less, can often be considered more rare to a customer and fetch a higher price.


  • Color –The world’s foremost diamond authority, the Gemological Institute of America, uses a grading scale that ranges from the most rare and valuable colorless “D” to the highly colored “Z”. However some colored diamonds, especially saturated pinks, blues, and greens, can be considered more rare than diamonds with less color.


  • Clarity – Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Diamonds graded Flawless don’t have any of these visible clarity characteristics when examined under a microscope. Flawless diamonds are so rare that it’s possible to spend a lifetime in the jewelry industry without ever seeing one.


  • Cut – The value and appearance (sparkle, brilliance and fire) of a diamond depends more on cut than any other factor. Cut refers not to a diamond’s shape (e.g. round, oval, pear, etc.) but to a diamond’s proportions, symmetry and polish.