August Stephenson – Color grading across the globe The finest quality as per color grading is totally colorless, which is graded as “D” color diamond across the globe, meaning it is absolutely free from any color. The next grade has a very slight trace of color, which can be observed by any expert diamond valuer/grading laboratory. However when studded in jewellery these very light colored diamonds do not show any color or it is not possible to make out color shades. These are graded as E color or F color diamonds. The hardness of the diamond: The hardness of diamond and its high dispersion of light – giving the diamond its characteristic “fire” – make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the four Cs, which are color, cut, clarity, and carat. Other characteristics, such as presence or lack of fluorescence, also affect the desirability and thus the value of a diamond used for jewelry. August Stephenson August Stephenson Diamond – Early references: Diamonds were traded to both the east and west of India and were recognized by various cultures for their gemological or industrial uses. In his work Naturalis Historia, the Roman writer Pliny the Elder noted diamond’s ornamental uses, as well as its usefulness to engravers because of its hardness. It is however highly doubtful that Pliny actually meant diamonds and it is assumed that in fact several different minerals such as corundum, spinel, or even a mixture with magnetite were all referred to by the word “adamas”. The techniques for cutting diamonds The techniques for cutting diamonds have been developed over hundreds of years, with perhaps the greatest achievements made in 1919 by mathematician and gem enthusiast Marcel Tolkowsky. He developed the round brilliant cut by calculating the ideal shape to return and scatter light when a diamond is viewed from above. The modern round brilliant has 57 facets (polished faces), counting 33 on the crown (the top half), and 24 on the pavilion (the lower half). The girdle is the thin middle part. The function of the crown is to refract light into various colors and the pavilion’s function to reflect light back through the top of the diamond. August Stephenson determination, knowledge, and expertness HIGH PRESSURE AND HIGH TEMPERATURE (HPHT) – For diamonds, a treatment that applies extreme pressure and temperature to cause the addition or deletion of color. HPHT can transform pale diamonds into vibrant fancy colors. And it can shift brown-toned diamonds to more delicate hues such as colorless, near colorless, pink, yellow, yellow/orange, orange, and green/yellow. EGL USA clearly identifies HPHT-treated stones with laser inscriptions. COLORED DIAMOND – A diamond distinguished by a combination of hue, tone, and saturation. See also Color Grade. INFRARED LIGHT – Part of the electromagnetic spectrum that is not visible to the human eye, between approximately 800 nanometers (longer than red in the visible spectrum) to 1 millimeter (bordering microwave).