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61% table TIC on HCA and setting question =)

edwinchester

Rough_Rock
Joined
Aug 31, 2011
Messages
10
Hi Everyone,

You all have been really great. I can't wait to show off the ring once I get it on my GF's finger

So I'm looking at a diamond that has a 1.7 TIC grade on the HCA, with a 32.5 C and 41 P . 61 table and 59 depth.... its a GIA ex3... looks amazing in person. I just find it strange that it is bordering the range BIC ( if i change the crown to 32.4, its relabeled a BIC on HCA) but only gets a VG on light return, but an excellent on fire. i would expect the opposite right? Not a serious issue, I was just curious as to what the pros out there had to say. I mean, the bigger table is fine with me, i went digging on the AGS site, and looks like the dimensions from the GIA cert would match an Ideal cut on AGS for the table size. I was just wondering why the light return was VG instead of EX and the fire was ex instead VG?

Also, its being set in a setting that has it open on two sides, will this hurt or help performance? I keep finding conflicting info about light performance with settings.

thanks all! didnt know how much went into diamonds before i came to ps. you are all awesome. I will post after i get it. it will be a few weeks though!
 

Stone-cold11

Super_Ideal_Rock
Joined
Sep 9, 2008
Messages
14,069
Should be fine, HCA is a rejection tool not a selection tool.

The setting is fine, a well cut stone mainly reflects light coming from above the girdle. Lesser cut will suffer some performance loss with enclosed setting.
 

edwinchester

Rough_Rock
Joined
Aug 31, 2011
Messages
10
Thanks, for replying, I'm definitely not worried about the diamond, I was just curious about why the TIC (Near BIC, with a 61% table) would have a EX fire and VG light return. I guess, from what I've been reading, I thought it would be the opposite.

Thanks again!
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,109
Numbers are fine. You'll want more info than just what's on the GIA report - GIA averages those numbers around eight sections of diamond, then rounds, then prints to the report, so without more info - scan, photos, etc. - we have no idea what sorts of ranges went into those averaged, rounded values.

It's a GIA XXX - it's not going to be an ugly stone, period. But without more information on A) the details of the stone's proportions, and B) what YOU like to see, we can't really tell you about whether it's likely to be a good match for your priorities and preferences...

Questions - how big is the stone, what is girdle, and what is lgf? If it's a smaller stone w/ a thin girdle I would recommend confirming with the vendor that there are no setting/wearing durability risks given the shallow crown (with a bigger stone this is less of a concern, since girdle is measured as a percent of diametre, 1% of 9mm is objecively much more than 1% of 5mm, though I would still recommend checking with the vendor!)


Regarding the HCA - I know what you are talking about, and I personally disagree with that statements as well. Whether a stone returns white light, coloured light, any light is predominantly dependent on the environment lighting - in spotlights all stones will show coloured light, in diffuse office lights all stones will be white, it's in the in-between types of lights that different types of proportions can create different "looks" and different types of light return. I have a shallow 60/60type 0.8ct w/ longer lgf (so thinner mains) and I do find that it shows less coloured light output in most light types than my other higher-crown type stones. It does, however, look *brighter* in almost all types of lights - it's a bright white dot even in the dimness under a desk. One type isn't better than the other - just different, which is best for you of course depends on what you like to see.

Long story short - as SC says, don't worry too much about the HCA result details - it's not a selection tool.
 

edwinchester

Rough_Rock
Joined
Aug 31, 2011
Messages
10
It's a GIA XXX - it's not going to be an ugly stone, period. But without more information on A) the details of the stone's proportions, and B) what YOU like to see, we can't really tell you about whether it's likely to be a good match for your priorities and preferences...


here are the other stats
a)12.5% crown - 32.5
43.5% p - 41

75% lower half and 50% stars
3% girdle medium to stk

7.48 x7.51x4.42
1.51 carats f vs2



Questions - how big is the stone, what is girdle, and what is lgf? If it's a smaller stone w/ a thin girdle I would recommend confirming with the vendor that there are no setting/wearing durability risks given the shallow crown (with a bigger stone this is less of a concern, since girdle is measured as a percent of diametre, 1% of 9mm is objecively much more than 1% of 5mm, though I would still recommend checking with the vendor!)

I'll definitely follow up with vendor, and thanks for mentioning for sharing your experiences with your 60/60. I hope i didnt come off sounding worried, i was just trying to figure out how the HCA's labels/ grading combinations, and found it interesting. Garry did a really cool thing with that.

Anyways, thanks again, for the response! Also, am i correct in assuming that this would be an ags 0? given the 61%, 32.5c and 41p?
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,109
I meant more info not found on the GIA report - scan, photos, etc. The info on the report is either derived by calculation or averaged/rounded.

AGS uses 3D ray tracing simulation to determine final cut grade as well as proportion charts, so no way to know for sure w/o submitting to AGS.
http://www.agslab.com/proportion-based-cut-grade.php
 

edwinchester

Rough_Rock
Joined
Aug 31, 2011
Messages
10
Is there a category for this type of diamond? meaning, I know the crown isn't that high, so it wouldn't be a steep/deep, maybe a shallow/deep? its my first time buying a diamond, and am earnestly trying to figure the lay of the land.
 

yssie

Super_Ideal_Rock
Premium
Joined
Aug 14, 2009
Messages
21,109
edwinchester|1316283658|3019569 said:
Is there a category for this type of diamond? meaning, I know the crown isn't that high, so it wouldn't be a steep/deep, maybe a shallow/deep? its my first time buying a diamond, and am earnestly trying to figure the lay of the land.

It's neither too shallow nor too deep and more importantly the combo can yield a very pretty stone, if you like the type of light return those proportions will result in :sun:

GIA rounds lgf to the nearest 5% - but 75 is better than higher w/ these proportions, IMO - means larger facet area that's more steeply angled, and a bigger difference in angle btwn the lgfs and the mains - more potential for fire in this stone than w/ longer lgf.
 
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