-    The less color, the rarer and more expensive the diamond
-    The highest color grade is D (white/transparent), the lowest Z (yellow).

Grading a diamond´s color means categorizing the smallest differences in color shade. This is usually done by comparing the diamond with a color master set of diamonds. The diamond grader compares the color face down in the laboratory under standardized light conditions one by one in order to find the diamond´s exact color shade.

In many cases the untrained eye does not even notice the differences in color. Yet, small differences in color can cause high high differences in prices. Most popular for the use in jewelry are near colorless diamonds (G, H, I, J). Traditional and still widely-known terms are “Top Wesselton” referring to the color range F to G and “Wesselton” describing the color grade H. While completely colorless diamonds are not only very rare, but also command the highest prices, many diamond lovers actually prefer slightly “warmer” colors like Wesselton and Top Wesselton.

The GIA color scale is today´s international standard nomenclature to describe a diamond´s color. However, the traditional terms as well as the IDC (International Diamond Council) terms are still in use. Origin of the yellow shade when going down the color scale is the occurrence of nitrogen: Nitrogen absorbs blue and violet wave lengths of the light.

This is how a diamond´s color is graded. A color comparison set is used to compare color shades under special lightning conditions: