The rarity of fancy colored diamonds

Fancy colored diamonds have shown a strong resistance to economic decline in the last several years. Their worth climbed during the recession, and it is still increasing in 2013. Many of the highest-grossing diamonds in recent auctions have all been colored. For example, The Pink Star - a fancy pink diamond - is estimated to bring in $60 million when it goes to auction. An orange diamond is projected to fetch $20 million. There's no question that these jewels have caught the eyes of buyers, but it's hard to say what makes them so popular.

The rarity of color

According to The Israel Diamond Industry, the supply of fancy colored diamonds has been on the decline. However, demand for them continues to increase. Dealers and private buyers alike have been snatching up these gorgeous gems. Rules of supply and demand in a free market dictate that the cost must then increase. Not to mention that many colored diamonds are rare. In general, the amount of colored gems is decreasing, however, some colors are rarer than others.

In the case of the fancy colored diamonds at auction, the multi-million dollar fetching stones are large. They are also perfectly cut and incredibly vibrant. A large, well-cut diamond will cost a pretty penny no matter the color.

Getting their color

One of the rarest colors of diamond is blue. According to the Smithsonian, only about one in 200,000 diamonds has any trace of blue in it. When a gem does, the shade is there because trace amounts of boron were introduced during the early stages of diamond formation.

Yellow to brown-yellow diamonds are created when nitrogen replaces some of the carbon in the gem.

Green diamonds are interesting because their formation includes radiation. When the rocks where the diamond is forming include natural radiation, the crystal structure gains impurities. These defect spots trap electrons, which interact with light to produce a green color. Most green diamonds have a higher concentration of color on their outer shells. This is because the rocks encasing the crystal were radioactive, so the effect did not penetrate all the way into the crystal.

Red or pink hues gain their color from a more material source. The gem experiences stress on its journey toward the earth's surface. The stress produces defects that trap electrons in a unique way to produce the color.