We'd like to say that there are only two instances that we consider blue fluorescence to be a negative factor... The first being the 2% of gem quality diamonds which exhibit such high degrees of fluorescence that the diamond exhibits a foggy or milky appearance, Robin's D color 2.54 carat marquise exhibits Distinct Blue Fluorescence which is beyond the parameters of Strong Blue and if not kept perfectly clean it can appear milky... We picked it up because it makes an excellent "teaching stone" for us to play with... The second instance is not really a negative visual characteristic from such an obvious perspective... Basically a D color diamond with strong blue fluorescence "has the potential" to "face up" like an E color stone... Thus you've paid a D color price for a diamond that "faces up" as if it were an E color... Medium blue fluorescence does not seem to have this effect, but sometimes a strong blue stone will... Similarily, strong blue fluorescence in an E color stone has the "potential" to make the stone face up like a D or very close to it on the high side of the scale for the E color range... In the days of old, D/E color diamonds that exhibited medium to strong blue fluorescence were called "blue white" diamonds and were heavily sought after... But then disreputable jewelers started using blue light bulbs to "create" blue-white diamonds when they didn't have any in-stock and the public began to question the integrity of diamonds with fluorescence... We find most fluorescent diamonds to be quite pretty, especially when viewed in direct sunlight from a side profile, but this is a matter of personal taste... One of our clients from Korea told us that fluorescent diamonds are considered to be "bad luck" there because they are "possessed" - while he had no problem with the concept as a member of the "new generation" he said that his grandparents would simply lose their minds...
Although blue fluorescence is our favorite common hue, white is also acceptable to us as it seems to have no negative impact on the diamond in the faint to medium ranges... We're not fond of medium to strong yellow fluorescence because it can make a stone face up a little yellower than it is, but it is an attractive trait for people who prefer warmer looking stones than the icy white that we prefer... We consider faint fluorescence of any color to merely be an identifying characteristic... Red fluorescence is quite rare and actually demands a premium in the market! No, we don't have a picture of it, but we think that RockDoc or OldMiner might... hint... hint...
