Depth % & Fluorescence???

[met]

Depth Percentage? Is the rule hard-core 61% or less on a round diamond???

What about Fluorescence? I heard it is not good to have any and some said it is??? I am confused?

thanks.

 

[atroop711]

some fluor (very strong blue) can look milky..but not all. I have a strong blue fluor stone and LOVE IT..In my opinion makes my H color look whiter. Some ppl LOVE fluor and some don''t. I think it''s all a personal pref. It''s not bad to have it..just make sure you have the stone checked. There is lots of info on fluor on this site and lots of post on it too.

GL

 

[stone-cold11]

Ditto on fluor. Some can make the stone look oily/hazy, these are very rare and I think know in trade as over blue.

Depth, just try not to go too deep, 62.3% is usually the limit for GIA before the cut grade is down graded, more will make the stone face up smaller. The angles and table size are more important to the performance of the stone.

Use the cut adviser if you are unsure to reject poor performer. Score of lower than 2 are worth considering, staying with the overlap of GIA Ex and AGS Ideal cut grade is reasonably safe, and should be further looked into in person or get an Idealscope image if viewing in person is impossible.

https://www.pricescope.com/cutadviser.asp

 

[chictomato]

hi I just bought a medium fluorescence E color diamond. Its really beautiful and sparkly. When comparing side by side with a non fluorescence E color. I honestly do not see any difference The jeweler I went to show me about 5 pieces of med-strong blue fluorescence, D-F color diamond. Yes, I do see tint of blue in strong fluorescence diamond regardless of the D,E,F color.I have to state that they are sparkly too. But its in one "triple excellent" Gia D color, strong fluorescence, I witness the "hazy effect". I am a real supported of medium fluorescence. I am upgrading my current pair of RB to med fluorescence too!

 

[Lorelei]

Date: 8/21/2009 6:25:17 PM
Author:met
Depth Percentage? Is the rule hard-core 61% or less on a round diamond??? No, you can go deeper, my personal cutoff is 62.4%, on a fiery ideal cut type diamond you can go deeper still but the trade off is loss of face up size.

What about Fluorescence? I heard it is not good to have any and some said it is??? I am confused? Rarely strong or very strong blue can make a diamond look cloudy but to put this in perspective, an expert vendor whom has been in the business for many years says the amount of '' overblues'' he has seen out of the thousands of strongly fluorescent diamonds he has dealt with could be counted on the fingers of his hands.

thanks.

 

[ct-appr]

The determination of the cut quality of a stone includes several important factors. These factors (crown angle, pavilion angle, depth, girdle thickness etc.) work together to create a beautiful stone. It''s not just the depth, they must all be in balance.

As for fluorescence, my daughter just became engaged and her stone is a G color, ideal cut, with weak blue fluorescence. It lights up the room! Strong fluorescence may make a white stone (D-E color) look a little milky.

 

[denverappraiser]

Once upon a time fluorescence was counted as a feature. ‘Blue white’ referred to the blue fluorescence and it traded at a premium as evidence that the stone was among the best. That was then, this is now and it seems to have fallen out of favor. As has been pointed out above, with the exception of a small group of strong blues known as ‘overblue’ that can take on a cloudy appearance in sunlight, you will not see any affect from fluorescence in normal lighting environments. Most people who don’t spend a lot of time in the disco or the tanning salon never even notice the level of fluorescence in their stone unless some gemologist tells them about it. The good news is that strong blue and even medium blue now trade at a discount because of internet customers buying off of lab reports who refuse to buy them. For people willing to do the legwork to rule out the overblues, this makes fluoro an area to look for potential bargains. That’s not a problem, it’s a feature.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[John P]

My experience leads me to believe the "fluorescence haze" scare is blown out of proportion.

Long ago the Premier Mine in South Africa (since renamed the Cullinan) had a stretch where a percentage of the rough coming out was overblue. This was prior to the emergence of Australia and Canada as diamond-producers so the presence of those diamonds in the pipeline was easier to notice. The result of that period of time is the warning you can still hear from every chain store sales clerk today, even though such overblue examples are exceedingly rare now.

In 1997 the GIA couldn't find enough examples to include them in their comprehensive fluorescence study (page 257). And a 2008 survey of notable appraisers (including Rich, Neil and Dave who post here) found them rare; "bordering on an obscure anomoly" (section II). It's also noted that you are likely to see more in older jewelry, which is in-keeping with the above.

We buy rough with regularity. There are certainly crystals with fluorescence we consider not-right for our purposes but on the whole fluorescence is either a non-factor or, in many cases, a positive for us. We regularly produce S and VS fluorescent diamonds (AGS standard) with no compromise. Our experience shows there is a niche of clients who seek out such diamonds for their appeal.

- I'd be remiss if I didn't note that Garry got answers ranging from "a small fraction" to "almost all" diamonds with VS fluorescence look oily (survey). I'd like to visit the "almost all" respondant to see what he or she is seeing; crystal growth, graining & dense pinpoint clusters can also make a diamond look hazy/less transparent. I wonder if some scapegoating is occuring. If not maybe that person lives in the "Overblue-muda Triangle"

... I'd love a vacation there.

With the above said, our company does rejects some fluorescent rough crystals. So do others. Yet that rough winds up somewhere. So even though I consider the scare bigger than the reality it won't stop me - or any responsible pro - from due diligence in this area.

 

[John P]

Date: 8/22/2009 11:15:08 AM
Author: ct-appr

The determination of the cut quality of a stone includes several important factors. These factors (crown angle, pavilion angle, depth, girdle thickness etc.) work together to create a beautiful stone. It''s not just the depth, they must all be in balance.

Nicely said.

 

[diagem]

Date: 8/22/2009 11:54:02 AM
Author: denverappraiser
Once upon a time fluorescence was counted as a feature. ‘Blue white’ referred to the blue fluorescence and it traded at a premium as evidence that the stone was among the best. That was then, this is now and it seems to have fallen out of favor. As has been pointed out above, with the exception of a small group of strong blues known as ‘overblue’ that can take on a cloudy appearance in sunlight, you will not see any affect from fluorescence in normal lighting environments. Most people who don’t spend a lot of time in the disco or the tanning salon never even notice the level of fluorescence in their stone unless some gemologist tells them about it. The good news is that strong blue and even medium blue now trade at a discount because of internet customers buying off of lab reports who refuse to buy them. For people willing to do the legwork to rule out the overblues, this makes fluoro an area to look for potential bargains. That’s not a problem, it’s a feature.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

Neil..., I consider the above highlighted a side-effect to the real reason (IMO) which was mentioned in Garrys article:

http://journal.pricescope.com/Articles/73/1/Blue-Fluorescence-in-Diamonds.aspx

"Many small and also large influential branded jewellers, including Tiffany & Co, do not stock diamonds with ‘Strong’ or ‘Very Strong’ fluorescence. One reason could be that big companies buy in large quantities ‘by system’ as a matter of supply chain simplification. This could contribute to a negative message perceived by dealers and consumers, as mentioned by Elly Rosen, such that there must be something wrong with fluorescent diamonds. There is abundant anecdotal evidence that salespeople in stores where there is a policy not to sell strongly fluorescent diamonds denigrate the goods of competitors who offer strong and very strong blue fluorescent diamonds."

 

[John P]

Date: 8/22/2009 1:23:05 PM
Author: DiaGem

Date: 8/22/2009 11:54:02 AM
Author: denverappraiser
Once upon a time fluorescence was counted as a feature. ‘Blue white’ referred to the blue fluorescence and it traded at a premium as evidence that the stone was among the best. That was then, this is now and it seems to have fallen out of favor. As has been pointed out above, with the exception of a small group of strong blues known as ‘overblue’ that can take on a cloudy appearance in sunlight, you will not see any affect from fluorescence in normal lighting environments. Most people who don’t spend a lot of time in the disco or the tanning salon never even notice the level of fluorescence in their stone unless some gemologist tells them about it. The good news is that strong blue and even medium blue now trade at a discount because of internet customers buying off of lab reports who refuse to buy them. For people willing to do the legwork to rule out the overblues, this makes fluoro an area to look for potential bargains. That’s not a problem, it’s a feature.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

Neil..., I consider the above highlighted a side-effect to the real reason (IMO) which was mentioned in Garrys article:

http://journal.pricescope.com/Articles/73/1/Blue-Fluorescence-in-Diamonds.aspx

''Many small and also large influential branded jewellers, including Tiffany & Co, do not stock diamonds with ‘Strong’ or ‘Very Strong’ fluorescence. One reason could be that big companies buy in large quantities ‘by system’ as a matter of supply chain simplification. This could contribute to a negative message perceived by dealers and consumers, as mentioned by Elly Rosen, such that there must be something wrong with fluorescent diamonds. There is abundant anecdotal evidence that salespeople in stores where there is a policy not to sell strongly fluorescent diamonds denigrate the goods of competitors who offer strong and very strong blue fluorescent diamonds.''

Bingo.

 

[diagem]

Date: 8/22/2009 12:41:29 PM
Author: John Pollard

My experience leads me to believe the ''fluorescence haze'' scare is blown out of proportion.


We buy rough with regularity. There are certainly crystals with fluorescence we consider not-right for our purposes but on the whole fluorescence is either a non-factor or, in many cases, a positive for us. We regularly produce S and VS fluorescent diamonds (AGS standard) with no compromise. Our experience shows there is a niche of clients who seek out such diamonds for their appeal.

I just want to add that in the "rough side of the moon" fluorescence is not considered less expensive it just widens the range of possibilities/availabilities in finding high quality rough on the open market...

An option I take advantage of as much as I can

.