It does not appear to make the diamond look cloudy under normal light. Hi Warren75, In general the trade discounts D, E and F colored fluorescent diamonds, but a GIA survey of experts and consumers found a slight preference for fluorescent diamonds. If your diamond doesn't appear oily or cloudy, it shouldn't be a problem for you. And its a good idea for a second opinion. Spend a couple more dollars and get a independent appraiser to examine it.
Mistakes do happen.
However, GIA sells a UV light unit to the trade that puts the lamp within 3 inches of the diamond. Many stones graded inert by the labs will definitely fluoresce under closer, more intense UV lighting conditions. You can expect independent gemologists to more harshly grade UV fluorescence since they generally have not been taught what the GIA lab actually does, and falsely assume the units sold by GIA duplicate the actual GIA-GTL methodology. A little UV fluorescence is not much of an issue. A lot may become a definite point of argument in a negotiation.