Pricing a D-J colored stone with blue fluorescence...

[Dancing Fire]

clarity and weight being equal.

This is my wild guess on the price difference between a (none/negligible) stone vs a stone with blue fluorescence.

Faint...0% to -3%
Med....-7% to -9%
Strong...-10% to -12%
Very strong...-12% to -15%

 

[Rockdiamond]

Interesting discussion DF!

We'd really need a spreadsheet.
Here's why, there's going to be so many areas where the differences are not consistent
In a D/VVS1 Inert versus SB the difference in percentage is far greater than in D/SI2

Also the relative differences vary by color
In a J color stone an MB can trade at the same price as an inert.

 

[diamondseeker2006]

I think the discount range might differ based on color range, though. I mean, fluoro in an I-J is a pretty good thing whereas purists would see it as bad in D-F.

Ok, RD just said what I was posting.

 

[Dancing Fire]

Maybe more accurate if I had said from H-J colored range?

 

[Rockdiamond]

Maybe more accurate if I had said from H-J colored range?

It would be easier to plot results because the amount of variables decrease.
For example- the aforementioned VVS- in a D bug difference based on FL.
IN a J very little ( if any) difference based on FL.
There are certainly cases of I-J color FL stones bringing higher prices than other I-J inert stones of the same size color and clarity.
On a stone like your Octavia DF- the FL is truly not relevant due to the rarity, and who cut it.

 

[Texas Leaguer]

I think David alluded to this, but just to add that the biggest penalties are in collection goods. DEF with VVS to FL

Dropping down into the lower clarities the penalties decrease. Lower colors and clarity combos is where you can see prices firm up and even go a little north in some cases.

I will echo a comment that Denver Appraiser made recently, that the growth of internet shopping is having a chilling effect on values. While some folks love fluorescence and seek it out, there is a much bigger group of internet shoppers that avoid it. With huge virtual inventories to browse through, many of those shoppers just put the "none" filter on. This is leading to liquidity problems for fluoro stones. Some might see this as a benefit as it is further depressing prices, perhaps artificially, making fluoro stones even more affordable.

 

[Rockdiamond]

Great point Bryan.
It also affects Fancy Yellows
I won't even look at FLY, FY or FIY stones with MB or SB
Taking a big picture look it really does hurt both consumers and the diamond business as a whole.
It hurt's consumers by eliminating some extremely attractive well priced stones.
it hurts the business as it makes things even more lopsided.
If you look at the existing inventories t's getting more and more lopsided with otherwise beautiful diamonds being rendered un-salable due to aspects that are negligible in real life.

 

[diamondseeker2006]

Hmmm, sounds like a good time to shop for a stone with SBF.

But what I wonder is, in what color grade would one get the most benefit. Like if I color doesn't get much discount for FL, then would an H with SBF be close to the price of an I color without it???

 

[Texas Leaguer]

I agree David that this property is misunderstood and as a result value and liquidity are unfairly punished.

Seems to me in the research I have done that the labs easily solve the two biggest problems that generate the uncertainty that devalues these stones.

First, they should report on transparency. They could easily do this in the comments field. For instance if it is true that fluorescence rarely causes milkiness, then if the report did not mention it a customer could buy that stone (on the internet, from a cert) without that concern.

Second, they should return to the practice of grading color in a UV free environment by covering the lamps with a UV filter or increasing the grading distance from the lamps. This would eliminate the concern for over-grading of color that is an important contributor for the price penalty.

If they were to implement these two simple procedures they would largely correct the uncertainties that cause the imbalances and fluctuations in the market. Future values would be more predictable and liquidity could be more accurately assessed. Currently traders predicate offers on worst case scenarios. And many traders just won't buy them at all because of liquidity concerns.

 

[Texas Leaguer]

Hmmm, sounds like a good time to shop for a stone with SBF.

But what I wonder is, in what color grade would one get the most benefit. Like if I color doesn't get much discount for FL, then would an H with SBF be close to the price of an I color without it???

It's a good question DS. The real opportunity is not in the primary market. Liquidity problems are compounded in the resale market.

I would probably aim for a high color and clarity with a great cut (of course) and make sure it did not have any transparency problems and can be verified not to to be over-graded for color. F VVS2 would likely be suffering under the effects of maximum discount. (You can see where the over-grading of color issue would be critical because if the stone was really a G or H all the assumed price benefit would evaporate.) I would be looking for essentially the same attributes in either the primary or secondary market but the secondary market is where you could really score big.

 

[diamondseeker2006]

Thanks, Bryan, that is really interesting. Aside from the virtual impossibility of happening upon a well cut stone second hand, I still think an F VVS with FL is still going to cost significantly more than say an I color, so that might not be practical to do. Probably the best cut second hand stones would come from high end jewelers originally, which would mean there aren't many with SBF considering the prejudice against FL among jewelers in general. I am thinking of stones such as emerald cut, which are sooo hard to find well cut under any circumstances. That would be quite a dream to have a well cut F VVS with FL, though!

 

[Texas Leaguer]

Thanks, Bryan, that is really interesting. Aside from the virtual impossibility of happening upon a well cut stone second hand, I still think an F VVS with FL is still going to cost significantly more than say an I color, so that might not be practical to do. Probably the best cut second hand stones would come from high end jewelers originally, which would mean there aren't many with SBF considering the prejudice against FL among jewelers in general. I am thinking of stones such as emerald cut, which are sooo hard to find well cut under any circumstances. That would be quite a dream to have a well cut F VVS with FL, though!

I really don't know what the prospects are out there. But it would be interesting to troll around. You could also potentially find a re-cut candidate - there are some great cutters on the forum that could tune it up.

By the way, I am not advising anyone to do this. There is your time to think of as well as significant risk. You would really have to know what you are doing.

 

[Dancing Fire]

First, they should report on transparency. They could easily do this in the comments field. For instance if it is true that fluorescence rarely causes milkiness, then if the report did not mention it a customer could buy that stone (on the internet, from a cert) without that concern.

Second, they should return to the practice of grading color in a UV free environment by covering the lamps with a UV filter or increasing the grading distance from the lamps. This would eliminate the concern for over-grading of color that is an important contributor for the price penalty.

TL...sounds good to me!... but are the chances for it to happen?

 

[Texas Leaguer]

First, they should report on transparency. They could easily do this in the comments field. For instance if it is true that fluorescence rarely causes milkiness, then if the report did not mention it a customer could buy that stone (on the internet, from a cert) without that concern.

Second, they should return to the practice of grading color in a UV free environment by covering the lamps with a UV filter or increasing the grading distance from the lamps. This would eliminate the concern for over-grading of color that is an important contributor for the price penalty.

TL...sounds good to me!... but are the chances for it to happen?

I think there is always a chance if it makes all the sense in the world to do it. But I'm an optimist. Do I think it will happen? No time soon. Why? Because I'm also a realist.

GIA has to do it. The other labs will synch up. For some reason GIA decided in recent years to depart from their traditional approach to color grading of fluorescent diamonds. Why they did that, nobody seems to know. Those that know probably would not say. But it probably has to do with what they see as best for their overall constituency. It's a business decision - some may call it politics.

They released a study in 1997 that basically whitewashed the whole issue of fluorescence. The takeaway was something like "for the majority of observers there is no appearance difference. Some seem to prefer fluorescence. In rare cases it makes the stone milky". They didn't talk about the color grading issue or the fact that there were liquidity issues. I think it was an attempt to help manufacturers move fluoro diamonds that were getting stuck in the pipeline. But the market didn't really buy it, so it continues to do what markets do and price things according to what they think might be the worst case.

Why GIA states that milkiness is a rare problem and they won't report on it makes no sense to me. If they want to help the flow of fluoro stones and it is such a rare problem, they should report those rare instances and give the other supposedly 'vast majority' their blessing.

 

[Dancing Fire]

Hmmm, sounds like a good time to shop for a stone with SBF.

But what I wonder is, in what color grade would one get the most benefit. Like if I color doesn't get much discount for FL, then would an H with SBF be close to the price of an I color without it???

DS, maybe you can compare the prices on BGD's site.

 

[Rockdiamond]

I agree David that this property is misunderstood and as a result value and liquidity are unfairly punished.

Seems to me in the research I have done that the labs easily solve the two biggest problems that generate the uncertainty that devalues these stones.

First, they should report on transparency. They could easily do this in the comments field. For instance if it is true that fluorescence rarely causes milkiness, then if the report did not mention it a customer could buy that stone (on the internet, from a cert) without that concern.

Second, they should return to the practice of grading color in a UV free environment by covering the lamps with a UV filter or increasing the grading distance from the lamps. This would eliminate the concern for over-grading of color that is an important contributor for the price penalty.

If they were to implement these two simple procedures they would largely correct the uncertainties that cause the imbalances and fluctuations in the market. Future values would be more predictable and liquidity could be more accurately assessed. Currently traders predicate offers on worst case scenarios. And many traders just won't buy them at all because of liquidity concerns.

Extremely well thought out post Bryan!

Transparency: Splendid idea Bryan-
The consideration I think GIA would face is that there's really a question of degree.
There are stones that are blatantly dull- in any light.
They would be easy to grade- because the deficiency is so obvious.
But I have seen stones that suffered no loss of brilliance in anything but direct sunlight- or being viewed in the dark under a UV light.
Some stones just have a tinge of this oiliness- others have an oily look that's easier to notice.
In this regard, if they were to implement such a grade, it would need to be quantified. Like a range from EX-POOR
The concept itself is phenomenal.

To the second point- and we do have a difference of opinion on this one-
I do not believe it's possible to eliminate 100% of UV in light.
I'm not a physicist, hopefully someone reading this can confirm or deny that.
Not to say that UV is consistent - clearly certain bulbs have more UV than others- and I'm not disagreeing that GIA might use different class of bulbs.
I will say that I find GIA color grading to be relatively consistent over time.
How I've tested this: sometimes a stone has an older report- so we need to replace the old GIA report.
When we submit, we generally submit "blind"- as opposed to giving them the older report.
I don't remember them changing any.
They have given some grades I considered to be incorrect.
I have had a few diamonds change a grade on recheck.
Mostly though, they stick to their guns.

Anyway, point is, I don;t think in a practical sense, GIA can eliminate all UV light sources.
A bigger deficiency in their methodology is the fact the color grade through the pavilion on colorless diamonds.
That practice produces far more inconsistent results IMO.