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GIA report on 2.55 round

sandy653

Rough_Rock
Joined
Sep 7, 2011
Messages
14
I've tried reading a ton and think this may not be that great of a stone/cut, but really wanted to get some insight from the poeple who really know what their doing. :D priced at $23,500. Still trying to figure out how to do the images right, hope the link is ok.

I get a 4.6 on the HCA tool, not sure ig I'm doing it right. If it is right that would be a bad number, yes?

**edited by moderator. please upload photos directly**

Thanks a ton :mrgreen:
 

Regular Guy

Ideal_Rock
Joined
Jul 6, 2004
Messages
5,954
Hi, Sandy, welcome.

I match your HCA numbers. Whenever the pavilion pushes beyond 41, it's not likely to be good news.

Seeing comparables here, also:

https://www.pricescope.com/diamond-search-results/161416

you'll find that most any GIA option, compared to on here, will cost less. Oops...check that...I forgot to see there were two pages of options, putting your option priced about in the middle.

But the HCA score would stop me cold.

Regards,
 

sandy653

Rough_Rock
Joined
Sep 7, 2011
Messages
14
Thanks regular guy appreciate the info.

Additional question would be does the high pavilion number decrease the amount of light reflected back and thus giving you a lower "bling factor". Curious how it works and that diamond is off the list now.
 

Regular Guy

Ideal_Rock
Joined
Jul 6, 2004
Messages
5,954
Sandy,

Although I think complementary angles drives whether or not light is reflected back or not, in which case...I think on its face there may not be innately the problem you are suggesting...since we do find with the frequent use we are happy to give the HCA, this thread by Garry:

https://www.pricescope.com/communit...-effects-of-dirt.26140/?hilit=shallow earring

gives further support for the rationale of eliminating pavilions going much beyond 41.

But, with any luck, some more sciency types will come along and help further...

Ira Z.
 

sandy653

Rough_Rock
Joined
Sep 7, 2011
Messages
14
Thanks again Regular guy.

Does anyone know how I can check this when the culet just says very small .35 - 1.05 which rates it fron good to excellent.

2.18ct round brillant
H
VS1
8.5 x 8.44 x 5.07mm
depth - 59.9%
table - 60%
crown - 13.3%
pavilion - 44%
crown angle - 33 degrees
pavilion angle - 41.6 degrees
girdle - thin to medium
polish - very good
symmetry - very good
Fluorescence - N/A
culet - very small
cut grade - ideal
comments - ideal cut

@ $25k it seems over priced for a EGL cert

OR

2.03 ct round brilliant
G
\VS2
8.39 x 8.3 x 4.84 mm
Depth - 58%
table - 60%
crown - 12.7%
pavilion - 42.3%
crown angel - 32.3 degrees
pavilion angle 40.5 degrees
girdle - thin to medium faceted
polish - excellent
symmetry - excellent
flourescence - medium blue
culet - n/a

Thank you
 

sandy653

Rough_Rock
Joined
Sep 7, 2011
Messages
14
sorry, must be tired found the HCA -

4.8 score on the first one

and

The second one has a 1.6 score

Does anyone see any glaring problem with #2 since it passes the HCA, it is an EGL cert
 

crbl999

Shiny_Rock
Joined
Jan 21, 2010
Messages
447
I wouldn't waste any time looking at EGL stones. EGL is known to be very loose on grading and a G VS1 could be a K SI2. Stick to GIA and AGS. If you would like some help finding a stone post your specs and budget and we'll be glad to assist.
 

sandy653

Rough_Rock
Joined
Sep 7, 2011
Messages
14
Thank your for the help, I assumed so on the EGL. Just wanted to make sure.

Budget needs to stay under 25k although that is a very nice diamond.
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,101
sandy653|1315492907|3012692 said:
Does anyone see any glaring problem with #2

way way way too shallow. It'll go black all over when you lean over it to admire (facets that in a differently proportioned stone are reflecting the things around you, the things over your ear and above your head at close range will in this stone instead reflect what's directly in front of them, like mirrors - you, your hair/face/clothes, and at that close range you're a poorly-lit dark blob from the front)


sandy653|1315428072|3011985 said:
Thanks regular guy appreciate the info.

Additional question would be does the high pavilion number decrease the amount of light reflected back and thus giving you a lower "bling factor". Curious how it works and that diamond is off the list now.

That's exactly what it does - diamonds sparkle from face-up because light enters, is reflected around inside the stone, and exits out the top to your eyes. There's a narrow range of angles the bottom (pavilion) facets can be to keep the light hitting those facets at greater than critical angle (which allows internal reflection, otherwise the light would just exit out the back), mess with the pavilion facet angle too much and light starts to do just that - exit out the back, instead of being internally reflected.

ETA: just saw regular guy provided a link!
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,101
sandy653|1315546220|3013354 said:
Looking at the one you posted, thank you

Additonally, can someone tell me how an AGA cut class 2b can get an HCA of 1.4. How does a non-ideal cut diamond reflect so much light back to be a 1.0? I have searched, but have not found an answer yet

http://imageshack.us/photo/my-images/692/ringjreverejewelers.jpg/

Again no good - super shallow crown + vthin girdle = huge chipping risk

HCA is not designed as a selection tool - just to help you quickly weed through a large inventory. You know that by hacking through you're going to miss some beauties, but you've got to start somewhere... HCA score does not guarantee beauty (or lack thereof). John Pollard calls it a chalk outline of a person, it's a good analogy - gives you a vague idea, can help you eliminate, but definitely nothing concrete enough to decide one way or another.

HCA, AGA tool, GIA, AGS grading - all different tools, w/ different specifications, requirements, priorities. They overlap in some ways, not in others - depends on what you're looking for, and on the stone in question specifically.
 

sandy653

Rough_Rock
Joined
Sep 7, 2011
Messages
14
Thank you Yssie, I did have concerns about the very thin girdle, but did not know about the shallow crown problem. I'm guessing that should be kept up around the 34 degree angle then.


Additionally the diamond you posted has an HCA of 2.3 or did I do something wrong? I was under the impression to never go above 2.0.
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,101
sandy653|1315547083|3013368 said:
Thank you Yssie, I did have concerns about the very thin girdle, but did not know about the shallow crown problem. I'm guessing that should be kept up around the 34 degree angle then.
girdle thickness is measured as percentage of diametre - you're looking at pretty large stones, so a very thin girdle is not going to be as thin, in mm, as in say a 0.5ct stone... it will reduce cut grade though.

I'd say stay over 32.5, 33ish (w/ complementary pavilion) for a bright stone w/ lots of white light return (at the expense of some coloured light return in some types of lights compared to other stones of similar size w/ higher-crown proportions) - definitely would want to have a vthin girdle vetted by a professional w/ say a 33crown. GIA is just telling you about the thinnest part of the girdle - doesn't tell you if just a tiny portion is vthin and the rest is medium, or if lots of it is vthin, or if an inclusion like a natural is the reason it's vthn in that area (though you have the inclusion plot, and if you have the stone in hand all these things will be enough for the experienced to determine)
 
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