Fancy color diamonds have always been much rarer and more desired than their colorless cousins, the secret of their shine being in exotic trace impurities in the carbon crystal. But recent years have seen the prices of all but the commonest yellows spiral beyond belief while their availability declines.

In the fancy colors, it is very difficult to see them on the market. Very attractive blues and orange diamonds are extraordinarily rare and hard to find, worse than in a long time. There are still plenty of yellows, but the unusual, attractive goods we once had access to, we don’t see them any longer. 

Prices are still expensive for very nice fancy color diamonds. There is a very stable market in very fine goods. The more available goods are in the yellows and browns. … We see a lot of browns, but unless they are very attractive brown-orange goods, they don’t command high prices. Prices are a little bit softer in those. 

These fancy colors are unique and rare. All fancy color dealers are looking for the same goods; there’s a huge shortage, more than I’ve seen in many years. There’s still demand, but if you don’t have the goods it doesn’t help.”
Yellow diamonds are the most in demand because they’re the most available because they are the most affordable.

You can see in auctions that every auction is breaking previous records. The prices of blue diamonds are astronomical. What was rare two years ago is almost unavailable now—that is, blues that are over 1 to 2 carats. People may be holding onto what they have.
Intense or vivid colors, and fancy pinks or blues, are most in demand, but in the Asian markets all kinds of fancy colors are in demand without exception. Collectors go for vivid blues or greens even if there are imperfections inside.

There’s a wave of buying of high-end colored diamonds. Investors who still have millions of dollars in the bank are looking for a place to put their money.
The question of treatments of fancy color diamonds, and their detection if they are not disclosed as they should be, is a perennial irritant to this sector of the trade. High-pressure, high temperature (HPHT) treatments can turn colors in diamonds more vivid and intense, and these are often not disclosed.

There are many HPHT diamonds that are considered natural but are later found out to be treated.