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2.55 carat. Conflicting cut info. Who to believe?

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Gauge

Rough_Rock
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I am looking at a 2.55 carat round diamond. It has an AGS Excellent 1 cut grade, HCA of 1.6 (shows it in the range for both AGS ideal and GIA excellent candidates). However, Blue Nile lists the cut as only "very good". (Blue Nile has both "ideal" and "signature ideal" above "very good" for cut in their normal ranking system).

Who should I believe? In other words, Blue Nile seems to rate the cut grade significantly lower than AGS or the HCA value would indicate. Why would Blue Nile lower the cut grade of one of their own stones? Do they know something that may not be reflected in the AGS report or the HCA score? I don''t know if I should put more stock into the AGS and HCA values or Blue Nile''s seemingly self depreciated cut grade.

Here are the specifics of the diamond:

2.55 carat
color I
clarity SI1
depth % 60.3
table % 57
crown angle 34.2
pavilion angle 41.0
cutlet none

AGS report shows:
Cut Grade: AGS Excellent 1
light performance 0
proportion factors 0
finish excellent
symmetry ideal
 

InlovewithJHK

Shiny_Rock
Joined
Jan 12, 2007
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I just did a quick look on bluenile and found multiple AGS000 princess listed as only a "good" cut grade... I honestly think that they are trying to push their branded diamonds (sign. ideal) on people or they don''t like AGS graded diamonds... those are the only reason I could think of
33.gif
 

diamondseeker2006

Super_Ideal_Rock
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Date: 5/13/2007 7:43:42 AM
Author: InlovewithJHK
I just did a quick look on bluenile and found multiple AGS000 princess listed as only a ''good'' cut grade... I honestly think that they are trying to push their branded diamonds (sign. ideal) on people or they don''t like AGS graded diamonds... those are the only reason I could think of
33.gif
That is probably the reason. It must not be one of their in-house stones. In any event, the fact that it is AGS1 will mean to some that it is not "ideal". It has exellent instead of ideal on finish. Would this bother me? NO! I''d be very interested in that stone! However, I''d try to get it from a vendor who has a trade-in policy in case later you wanted to upgrade the stone. If the stone is in their virtual inventory, then it can possibly be accessed by other vendors.
 

diamondseeker2006

Super_Ideal_Rock
Premium
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I just looked up that stone and it appears that BN is the only one listing it. But it also has a thin to thick girdle, and that would also knock it out of GIA Excellent. So I''d say BN is trying to label stones accurately. That''s very good!
 

Regular Guy

Ideal_Rock
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Jul 6, 2004
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5,960
Guage,

I think only AGS is touching the diamond, and evaluating it specifically. Blue Nile, as InLovewithJHK is alluding to, is I believe classifying all diamonds with a certain set of parameters the same, regardless of looking at how one set of parameters might specifically offset another...which is more of what HCA does...and in the case of AGS...as it will do after having mapped each individual diamond.

If the diamond is being downgraded by AGS to 1 for finish, from 0, this sounds good to me...as the other factors are more critical to you...and yet you''d get some discount for the failure to reach 0. Otherwise, I doubt BN sets premium pricing with respect to their internal categories, too, but they may...which would provide further helpful discounting, relatively.
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
Good points in replies above. I think that Blue Nile's cut criteria/system is outdated.

Here they say:


If a GIA or AGSL certified cut grade is not available for a particular diamond, Blue Nile's proportional grading system will determine the diamond's cut. .
Obviously, AGSL cut grade is available for this diamond but for some reason Blue Nile's software missed it and assigned their own proportion-based grade, which is not very accurate.

Possible reasons for penalty can be Polish "excellent (1)" instead of "ideal (0)" and maybe girdle is "thin to thick".

There is nothing seems wrong with proportions and the price seems quite good comparing to other similar diamonds. I would suggest to ignore this automatically generated cut grade or inquire from Blue Nile rep about it or send it to independent appraiser.
 

Gauge

Rough_Rock
Joined
Apr 29, 2007
Messages
27
Thank you for all of the replies.

As pointed out, the girdle is thin to thick (.8% to 3.9%)faceted. How much of a concern is this? From my limited understanding, a thick girdle adds weight to the stone without increasing its diameter or noticeable size and is therefore undesirable. Is this correct? Any other negatives with a thick girdle? Is there any way to tell from the report whether a majority of the girdle is thick or a majority is thin?
The diamond seems to have a pretty good diameter or spread for this carat weight (8.87 x 8.92 x 5.36). Does this mean that the thick girdle should be less of a concern?

Here is the portion of the report showing the dimensions and the inclusions. Does any other negative jump out at anyone from this? The inclusions in this SI1 diamond look pretty big on the report. Can you tell from the report alone whether this diamond will be "eye clean"?

Diamond:

diamondforweb5.jpg
 

neatfreak

Super_Ideal_Rock
Joined
Feb 17, 2007
Messages
14,167
A too thin girdle can have durability issues too.

But really, if the experts on PS are telling you it's a good deal for this stone, NAB IT and bask in your good deal!
2.gif



As for the eye clean issue, you can't tell from the report. You'd have to get this diamond in hand to find out. That's why many people here prefer to work with vendors like Whiteflash or GOG who will do analyses for you and tell you if it's eyeclean before they send it out to you. I don't know that Bluenile can/will do this for you...
 

Gauge

Rough_Rock
Joined
Apr 29, 2007
Messages
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Since this diamond is only listed on Blue Nile, does that mean that other online dealers will likely not have access to it? Is it worth asking someone like White Flash if they can get it?
 

Pupper

Rough_Rock
Joined
Sep 1, 2006
Messages
41
Date: 5/13/2007 9:48:32 AM
Author: Gauge
Since this diamond is only listed on Blue Nile, does that mean that other online dealers will likely not have access to it? Is it worth asking someone like White Flash if they can get it?


From experience, I know Mark from engagementringsdirect.com can get it in for you & prolly for less $$; I''m not sure about WF tho...?
 

Paul-Antwerp

Ideal_Rock
Trade
Joined
Sep 2, 2002
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2,859
Date: 5/13/2007 9:16:03 AM
Author: Gauge
Thank you for all of the replies.

As pointed out, the girdle is thin to thick (.8% to 3.9%)faceted. How much of a concern is this? From my limited understanding, a thick girdle adds weight to the stone without increasing its diameter or noticeable size and is therefore undesirable. Is this correct? Any other negatives with a thick girdle? Is there any way to tell from the report whether a majority of the girdle is thick or a majority is thin?
The diamond seems to have a pretty good diameter or spread for this carat weight (8.87 x 8.92 x 5.36). Does this mean that the thick girdle should be less of a concern?

Here is the portion of the report showing the dimensions and the inclusions. Does any other negative jump out at anyone from this? The inclusions in this SI1 diamond look pretty big on the report. Can you tell from the report alone whether this diamond will be ''eye clean''?

Diamond:
The way in which AGS notes the girdle thickness nowadays (since the launch of the new light-performance-report), is sometimes confusing for people comparing this to stones graded by other labs.

AGS posts the smallest and the biggest thickness, thus the smallest thickness in the valleys (in this case 0.8) and the biggest thickness at the hill-tops (in this case 3.9%)

GIA posts the smallest and the biggest thickness in the valleys, which gives in comparison the impression of a greater consistency, and which gives in general much lower numbers.

HRD for instance posts the smallest and the biggest thickness at the hill-tops, which also gives the impression of a greater consistency, and which gives in general higher numbers.

To sum it up, the different way of noting a measurement does not mean that something is wrong. The thinnest point is not too thin, and the thickest point is definitely not too thick.

Live long,
 
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