Fancy Cognac Diamond A Simple Beauty A Cognac Diamond is actually a mix of orange and brown color. The Cognac Diamond gets its coloration from traces of nitrogen trapped inside when it is formed. Prices for a typical Cognac Diamond are usually 30% less than for the comparable white diamonds because they have been traditionally less popular.  Today the Cognac Diamond can be found in earrings, bracelets, necklaces and even engagement rings.  The Cognac Diamond turns out to be an excellent investment, because its popularity keeps on increasing and it`s rarer in nature, even more than a Yellow Diamond.