A diamond is deemed colorless for its capacity to absorb all light rays equally. These are identified as in the D to F range, and they have no detectable color, allowing the maximum amount of light to shine through the diamond. They are the most expensive.
Diamonds in the G to I range may appear to be colorless to the naked eye, but they exhibit a minuscule amount of yellow and are called Near Colorless. These may be more affordable and may appear to be just as brilliant as a colorless diamond.
J to M stones will exhibit Faint Yellow traces. Diamonds rated from N to Z in the color scale will show deeper yellowing, and even tinges of brown and gray.
For diamonds graded beyond Z color, this website will offer you indepth information.
That bluish sheen which can be observed in a diamond under ultra-violet lighting, is known as fluorescence: a quality that subtly conveys on a diamond its mysterious allure.
It is not well known that medium to strong blue fluorescence in a quality diamond will actually improve its brilliance and loveliness. Yet uninformed buyers are typically troubled by the mere mention of fluorescence in a stone.
The fact is that fewer than 10% of gem quality diamonds will exhibit this blue fluorescence either in an incandescent lighting situation or even when viewed in sunlight, which has strong ultraviolet properties.
There is no need to fret over fluorescence. In D – H color stones, fluorescence only rarely will make the diamond look cloudy. A Faint Yellow (J – M color) stone with good fluorescence will actually appear is if it is Near Colorless. So, for the price-conscious consumer, buying a yellowish diamond with strong fluorescence can actually be a gain.
Blue is the most widespread color of fluorescence. But green, yellow, pink, white and greenish-blue fluorescence are also found in diamonds.