The most rare of all of the fancy color diamonds is the red diamond, and these are considered priceless. The color red is created through extremely high pressure on the diamond causing tiny microscopic abrasions within the structure of the diamond. This effect is called graining, and it causes the appearance of red color by absorbing every color in the visible spectrum other than red. This is true of pink diamonds as well. The red is more intense and saturated and surpasses a vivid pink color grading. The majority of red diamonds are less than .50ct. in size. The world’s largest red diamond is known as the Red Shield, and weighs just 5.11cts. Many diamonds that are called red actually have modifying colors of brown or purple. These diamonds would be referred to as purplish red or brownish red. The modifying colors would be noted on the gemological laboratory report. Many color diamonds exhibit more than one color. These additional colors are called modifiers. Modifiers can either increase or decrease the value of a color diamond.