Worth considering a stone with only good symmetry?

[ks2012]

Is it worth considering a stone with only good symmetry? It has ideal proportions otherwise and has been given a GIA cut grade of very good.

 

[chrono]

It depends. Have you seen the stone or at least show us a picture? Stones with cut issues are usually dinged with a Good symmetry rating.

 

[ks2012]

I'm waiting on a photograph at the moment. Would I be able to see the symmetry problem on the photograph?

 

[chrono]

Sometimes. Sometimes, a dangerously thin girdle or some other cut issue is the cause of the rating.

 

[John P]

Is it worth considering a stone with only good symmetry? It has ideal proportions otherwise and has been given a GIA cut grade of very good.

1. There is no such thing as AGS "Ideal proportions" anymore, since AGSL switched to 3D light performance grading in 2005. Perhaps it's predicted to qualify for AGSL Ideal Light Performance based on cutting charts? Or maybe it's some other entity's definition of Ideal?

2. Good symmetry - on its own - falls into a range that is potentially eye-detectable, but doesn't necessarily detract from the diamond's ability to return light. As a manufacturer it does lower my confidence in the level of planning/care/tooling used to produce the diamond.

With the above said it's hard to give meaningful input without more information. Do you have a carat weight & grading report # - if so we can view the report online.

 

[John P]

Sometimes. Sometimes, a dangerously thin girdle or some other cut issue is the cause of the rating.

This is true. At the same time, the highest overall cut grade GIA will give a diamond with Good in a finish category is VG.

 

[ks2012]

Here are some numbers:

Depth: 61.5%

Table:54%

Crown Angle: 35.0°

Crown Height: 16.0%

Pavilion Angle:40.6°

Pavilion Depth:42.5%

Star Length:50%

Lower Half: 75%

Girdle: Thin to Medium (3.0%)

Culet:None

Polish: Excellent

Symmetry: Good

Fluorescence:Faint

 

[John P]

The basic numbers are promising. If this were a 3X diamond I'd give it a fair chance at being well-cut.

In this case - with the "G" finish grade - it's germane that I mention that most of the single numbers you provided above are actually averages of 8-16 separate measurements which are then rounded up or down; in some cases to the nearest 0.5 degree.

The only way to determine how much deviation from those average numbers exists from afar is with a scanned manufacturer's report - which is still subject to given error - or, better, a reflector view such as ASET / Ideal-Scope and (supplementary) H&A.

 

[ks2012]

Thanks John. Here is a photo if this is any further help.

 

[John P]

Thanks John. Here is a photo if this is any further help.

That is a help. The appearance looks to be in-line with careful cutting, making the "good" in symmetry potentially unimportant to appearance. But there are a number of things that can contribute to the grade, some of which are benign, some of which are not.

Have you asked the seller to provide insight here? It doesn't look off-round (though no mm were provided before). The culprits could be girdle wave (can't tell here), table or culet off-center (nothing to indicate that here...but see tilted table), PA or CA variation (need ASET or ideal-scope) tilted table (possible with some of the bezel reflections I see in the photo - but that could be a simple lens alignment issue) or extra facets on pavilion (can't tell).

The good news: With this photo capability I wager the seller can provide you with an ASET or Ideal-Scope. If that view checks out - and the seller can verify what caused the "G" in symmetry was a benign issue - you may have a winner with a bit of a discount already factored in.

 

[ks2012]

Thank you so much John. I will ask the vendor for more information