Patent ID: 7388656

Claim:
A method for color grading of a gemstone using a system with a computer program product, comprising: calibrating a display element to a specification of a white point of a CIE standard illuminant at a brightness level with a γ correction; observing an average color of said gemstone by the 45/0 condition under a standard CIE daylight simulator against a neutral background and surround; adjusting a hue, a lightness and a saturation value continuously to change a reference color of the display element by a color grader; calculating a color coordinate and a color notation from said hue, said lightness and said saturation value; applying said γ correction to a RGB tristiumlus value; calculating a RGB digital counts; assigning a corresponding color name from said calculated color coordinates by checking a color name look-up table; making a logical decision; displaying said assigned color name and said calculated color coordinates; and displaying a reference color on said display element.