Opinions on Two Stones - Steep/Deep Issue

[juniper2012]

Hello all. I apologize as I am a relative newbie at evaluating diamonds, but I've been looking at two round brilliant diamonds for an engagement ring and I was hoping to get some advice. Both are GIA certified diamonds that are approx 1.5 carats, SI1, rated triple excellent by GIA, with no flourescence, but I got a poor HCA score of 4.7 on the G colored stone. The proportions for the two stones are below, taken from the GIA reports. I'm being offered the G stone at about $800 more than the H stone as part of package with a wedding band, so was thinking of taking it, but not sure anymore because HCA score seems pretty bad. Weird thing is the G stone seemed to sparkle a lot and looked whiter in the store than the H stone. Is the G stone a bad steep/deep stone and would you recommend against it?

First Stone
Color: H
Depth: 60.8%
Table: 55%
Crown Angle: 33.5°
Crown Height: 15.0%
Pavilion Angle: 41.0°
Pavilion Depth: 43.0%
Star Length: 55%
Lower Half: 75%
Girdle: Thin to Medium, Faceted (2.5%)
Culet: None

Second Stone
Color: G
Depth: 62.1%
Table: 57%
Crown Angle: 34.5°
Crown Height: 15.0%
Pavilion Angle: 41.4°
Pavilion Depth: 44.0%
Star Length: 55%
Lower Half: 80%
Girdle: Thin to Medium, Faceted (3.0%)
Culet: None

 

[Amys Bling]

First off- jewelry lighting is very forgiving. I'd make sure to view the stones in more natural lighting as well.

Personally, I wouldn't go for a 4.7 on the HCA when spending that kind of money. Especially in an ERing stone I'd be staring down at all day how was the HCA on the other stone

 

[juniper2012]

The HCA score on the H stone was 0.9 Excellent. But for whatever reason, when I looked at that H stone in the store and on the street in natural lighting, it seemed a little dull, with dark spots around the center. The G stone also looked pretty good when I saw it.

Could the "Lower Half" percentage being 80%, or some other factor not listed in the GIA report, somehow help alleviate the light leakage from the crown and pavilion angles being the way they are? Alternatively, could the fact that the stone is a H color, make it look duller than the G stone, regardless of cut quality?

I reviewed some of the threads here on the steep/deep issue, and it is a little confusing since GIA gave both of these stones a Excellent cut grade, although I guess there is a range within that.

 

[MissGotRocks]

Steep/deep generally refers to steep crown angle with steep pavillion angle. Both of these stones have steeper pavillion angles but not crown angles so they probably don't really qualify as 'steep/deep'. However, the HCA will ding both of these stones because of the 41+ pavillion angles and the one stone with a 62+ depth.

The H color stone definitely gets the better HCA score but you didn't particularly care for the look of it. These are not the only two diamonds in the world to consider and frankly, I'd pass on both of them. Have you considered calling one of the PS vendors to see what they can find for you? I wouldn't limit myself to these two stones - there are many, many stones for consideration!

 

[Amys Bling]

Well then, keep looking. No one is ditching you to buy one of those two what is your budget???

 

[yssie]

The HCA score on the H stone was 0.9 Excellent. But for whatever reason, when I looked at that H stone in the store and on the street in natural lighting, it seemed a little dull, with dark spots around the center. The G stone also looked pretty good when I saw it.

Could the "Lower Half" percentage being 80%, or some other factor not listed in the GIA report, somehow help alleviate the light leakage from the crown and pavilion angles being the way they are? Alternatively, could the fact that the stone is a H color, make it look duller than the G stone, regardless of cut quality?

I reviewed some of the threads here on the steep/deep issue, and it is a little confusing since GIA gave both of these stones a Excellent cut grade, although I guess there is a range within that.

Those look like GIA numbers? GIA averages values around eight sections of stone, then rounds, then prints that rounded average on the report, so there can be a range of actual measurements around the stone that can nuance the way the stone looks and returns light. Without more info like a scan or some closeup pics we can't tell you more, but as MGR says different people prefer different looks, nothing wrong with that!

In *general* for RBs changes in pav have more "effect" than changes in crown, and GIA rounds pav up to nearest 0.2deg. And yes, lower half can absolutely change the appearance significantly! Check out this link for a quick tutorial on lower half facets (also called LGF on here) http://www.goodoldgold.com/Articles/MinorFacets/ GIA rounds LGF to 5%. GIA's EX cut grade is, as you observe, a range, but only one in a million GIA EXs will be an objectively unattractive/poorly-performing stone, and with those proportions neither of those are anywhere close to being that one in a million! Steeper pavilion combos that result in some light escape out the bottom/sides of the stone (pale/white in Idealscope pic) are frowned upon here, I personally have no objection to slight "leakage" as those stones will also show more coloured light return but that's a personal preference.


1. A reputably graded H will not be duller or darker than a reputably graded G.
2. Were both stones spotlessly clean all through the comparison? They should've been cleaned beforehand, and handled with tweezers or gloves - diamonds are grease and skin-oils magnets.
3. Clarity? Clouds/wisps in lower-clarity may impede brilliance