A champagne-colored cognac diamond.

If until now you imagined a diamond as a colorless stone, keep in mind that it can also be colored. And some of the most popular now are the marvelously beautiful brown-colored diamonds called Coqnac.

Look closely at such a champagne-colored diamond, and you will think that you are looking at a champagne glass with sunlight penetrating through its honey-colored thickness. Turn the stone sideways and a new and stunning hue will appear inside the stone. The brown color of diamonds was obtained due to iron and nickel, the amount of inclusions of which in the crystal lattice of the stone determines the saturation of the shade.

There is another category of cognac diamonds, called cape, which has nitrogen atoms in its structure. When crystallized, they give the stone a brown color. These minerals are considered lower quality because nitrogen reduces the transparency and density of the diamond.

Figure 1. Cognac diamonds

Champagne-colored diamonds were first discovered at an Australian mine in the late 1970s. Until the end of the century, they were classified as technical diamonds and used mostly in industry.

But everything changed in 2001, when at the Basel Fair a jeweler from Belgium, Pasquale Bruni, presented a collection of jewelry made of cognac-colored diamonds. Instantly, the demand and price for cognac diamonds increased several times, and no wonder!

The stones sparkling in the sun in a yellow or – much rarer – rose gold setting look simply marvelous.

There are two scales that are used to assess the color of champagne diamonds

Fig. 2. Ring with a cognac diamond

According to one of them, the shades of these stones are divided from C1 to C7, where C1 and C2 are light, C3 and C4 are medium, C5 and C6 are dark champagne, and C7 is cognac. On another scale used by the Gemological Institute of America (GIA), light champagnes are designated by letters N through V.

These are assigned to the lightest yellow hues of the stone. Medium Champagne is designated by the letters W through Z for light yellow and yellow stones. Dark champagnes and GIA cognacs have brown and dark brown hues and are at the base of the scale.

Most of them – more than 95% – are mined from the Argyle mine in Australia. There are also deposits in Brazil and South Africa. But already now the source in Australia is considered almost completely depleted.