Natural fancy white diamonds, or ‘opalescent’ diamonds, must not be confused with colorless diamonds, which are commonly denominated ‘white’ diamonds. Natural fancy white diamonds have an inherent snow-white color, giving them a translucent, ‘milky’ appearance, similar to that of opals. Pure white diamonds with no secondary colors are rare and highly desirable to dealers and collectors. They also come in brownish, bluish, yellowish or grayish nuances.
Read more about the origin of the color in natural white diamonds here.