15 replies to this topic

[barry]

Consumers shopping for diamonds both at B&M's and with Internet vendors are receiving conflicting and erroneous information regarding the effects of fluorescence on a diamond's visual appearance. The dispensed advice takes the following forms:

1. Fluorescence (FL) is bad, stay away.
2. FL in lower color diamonds, e.g.; I-J-K is a positive in that it will make the diamond face up whiter but only if the FL is faint or Medium, not Strong. In higher colors (D-H) it is detrimental; stay away.
3. Strong FL is to be avoided at all costs.
4. FL diamonds need to be priced and sold at a discount relative to comparable carat weight, color/clarity-cut diamonds that are non-FL.

Much of today's consumer attitudes and behavior regarding FL can be traced back to the Diamond Industry's perception of FL. Briefly, some diamond merchant's would look for near-colorless to light yellow diamonds with strong blue FL because they believed that such FL imparted a more colorless appearance under lighting with a high UV content.

In the late 70's during the diamond "bren" when prices skyrocketed daily (analogous to the Tulip craze of the early 1800's), some diamantaires observed that some gem diamonds with a very hazy appearance also fluoresced strong blue to UV radiation. These dealers started offering significantly lower prices for these "Milky D's (D color diamonds with very strong FL and reduced transparency) and very strong FL also termed "overblues". Gradually this perceived negative impact of FL spread downwards to encompass color grades as far as F. In addition, with the significant influx of Russian goods which contain Med to Strong FL into the market, this perceived negative effect of FL has been exacerbated.

Additional industry concerns about FL took on the following perceived factors:

1. Non-FL diamonds were thought to be more pure than FL stones,
2. Non-FL diamonds in the D-F color range were thought to be rarer than FL counterparts, and
3. The hazy appearance in the "overblues" must perchance also exist to some deleterious degree in weaker FL diamonds as well.

A 1993 South Korean TV "expose" on FL aimed at consumers further served to highlight these perceived negative aspects of FL.

Rapaport took these industry notions of FL one step further by codifying these artificially trade induced price differentials into his Rap pricing sheet, thus the diamond 'Bible' had spoken and all say Amen, brother.

The fact is that FL is not a negative in the diamonds; on the contrary it can be and is a very positive factor. Several of us in the trade have known and advocated this both in the trade. We do not price discount our Medium or Strong FL SuperbCert diamonds as there is no reason to.

In 1997, GIA conducted an extensive study on the effects of diamonf FL on visual perception. Consumers and tradespeople were both asked to evaluate the effects of FL on their visual perception and to note any meaningful distinctions between non-FL to FL diamonds of differing FL intensities.

The results of this GIA study were highly instructive and surprising. GIA found that non-trade observers ( akin to consumers shopping at their B&M jewelers) could not make ANY meaningful distinctions between non-FL to the FL diamonds and that FL diamonds had no overall effect on the diamond's color or transparency!

For the experienced observers that encompassed tradespeople, the strength of FL had no significant effect on the color appearence of the diamonds when viewed table-down (typical of lab grading). In the table-up position (which is the way consumers view the diamonds at B&M's and diamond showrooms), diamonds that were described as strong FL or very strong FL were, on average, reported to have a better color appearance than less FL stones. Strong FL was reported to have little impact on perceived transparency of the diamonds.

The link to this GIA study is here:

http://www.gia.edu/p...7_fluoresce.pdf

This is a very important study and should be required reading for both consumers and all diamond and jewelry professionals. There are no grounds to consider FL in a negative light and therefore no basis for price differentiation relative to non-FL diamonds.

The Earth is not flat.

Barry
www.superbcert.com

[TheRock]

Hi Barry,

Excellent post, very informative. I'll have to bookmark this one! The only thing I disagree with is item 3. "Strong FL is to be avoided at all costs." but that's just one mans opinion and we know how subjective this business is.

[barry]

Rock;

Thanks very much for your kind words. Just to repeat, I think this study by GIA should be required reading by both consumers as well as trade professionals.

BTW, #3 is not my opinion., but what consumers have told us and what we've seen bandied about by some "experts" that travel on several inet diamond forums.

Again, not so much their fault as it is the diamantaires in our industry.

Barry
www.superbcert.com

[jan]

Here is the flourescence chart that Rappaport did.

Jan
www.dbof.com

Attached Images

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[jan]

BTW we sold a strong blue flourescence recently and it was a very bright stone that got very high light performance. It was not greasy, milky or oily in the least. The client chose it by comparing it with other stones that had no fluorescence, but the light performance far outweighed the fact that it said strong blue on the paper.
It is something that is definitely worth looking at and comparing.


Jan
www.dbof.com

[barry]

There you go. I guess GIA was on to something back in 1997 .

Barry
www.superbcert.com

[Urlik]

[url="http://www.diamond.info/forum/index.php?showtopic=1413"][url]http://www.diamond.info/forum/index.php?showtopic=1413[/url][/url]

[TOWANDA]

To continue with the issue of my diamond glowing in the black light, HIGHFLY, you stated that this is an indication of the amount of fluorescence of the diamond. I looked up "fluorescence" in the glossary on this website and it said that diamonds with high fluorescence (emitting a bright blue color under a black light) should be avoided. Why is this? :(

[highfly]

"Avoid" is probably not the right word.

Diamonds with very high fluorescence tend to be sold for a discount over their non-fluorescent counterparts. Typically the discount is 10% or so, more for very high fluorescence. So while it's perfectly ok to purchase a diamond with fluoro, be sure you're paying the appropriate amount for it. Also be sure you are aware of the fluoro levels so you know what you're buying.

Keep in mind that just because fluorescent diamonds cost less does not mean they are not beautiful!! I actually prefer a little bit of fluorescence, so that the diamond changes color slightly when exposed to different types of light. Makes for a more interesting gemstone :-)

[Princess Tess]

I'm with highfly, I like a little fluorescence. It does seem to make the diamond more sparkly.

-Princess Tess

[Rhino]

Yea... I'd change that "avoid" word. Many consumers are turned off by the slightest mention of the word fluorescence due to misinformation being published on the subject when in fact it can be a very positive factor and in many cases increase value instead of decreasing it.

Cases where fluorescence should be approached more cautiously.

a. If it is described as being "strong" or "very strong".
b. If the color that it fluoresces' is a color other than blue (ie. yellow, green, etc.).

In these cases you will want to compare the diamond with others comparable stones that have no fluorescence or faint/medium. Then if you do not like the effect, simply pass.

In your case it sounds like you found out about this after the fact and it sounds like the fluorescence is strong or very strong based upon your description. If this makes you uphappy and you are not pleased with what you see, ask your jeweler if he has any upgrade policies and perhaps you can trade it in. Some jewelers do offer this.

Hope that helps.

[barry]

There is, unfortunately a tremendous amount of mis-information regarding the effects of fluorescence on a diamonds appearance, with concomitant and unnecessary price discounting of fluorescent diamonds. Sad to say, there are many in our trade that are guilty of this. The fact is that deleterious effects of fluorescence affect less than 1/2 of 1 % of all polished diamonds on the market. This mis-information is further propogated on internet forums by well meaning consumers who pick up on the postings of tradespeople.

A little known but extremely important and well designed study by GIA scientists clearly demonstrated that both consumers and tradespeople could NOT distinguish strong fluorescent from non-fluorescent diamonds in the face-up position under a variety of lighting conditions.

This important study is here: http://www.gia.edu/p...7_fluoresce.pdf

Required reading

Test on Monday

[Princess Tess]

Barry,

What was this guy selling then? He swore the "colorations" were caused by fluorescence...there were slightly yellow and a pink and (I swear) different shades of "white-ishness."

Curious-er and curious-er.....

The Mightily Confused
Princess Tess

[barry]

I believe the guidelines and restrictions apply to linking back to one's own website and for the purposes of promoting one's own product(s) and service(s).

The link I referenced was GIA's excellent study on fluoresence.

[Rhino]

Thanks for the clarification and YES that is an excellent article! Hey ... do I detect a little more gray in that beard?

[sparkllvr]

I've seen several links to articles on this forum and they seem to be allowed as long as they aren't self serving. Personally I've posted an article link too and actually prefer to read an article through a link than through someone elses potentially skewed viewpoint.

Tess: Hi! Just want to get to you about your fluorescence question. It's possible that the jeweler was using diamonds of different color shades, including variances in whites (i.e. more or less yellow) when they designed the pieces you saw. Could you have mis-understood the fluorescence angle? Just a thought.

Sparkllvr