Table in relation do depth, crown in relation to pavilion

[LaSuecia]

So I've been rhinking, and trying to read up on the relationships between the table and depth procent, and the pavilion and crown angles.

Now I know the scale for excellent is

Table 53-58%
Depth 59-62.3%
Crown 34-34.9
Pavilion depth 42.8-43.2

Is this correct?
How do all these numbers co-relate?
I'm thinking if you have a diamond that has a table of 57, a depth of 62.3 will maybe be too deep for it, perhaps a depth of 60 is to be preferd. Or a crown angle of 34 should not have a pavilion depth more than 43 ( just example numbers).
Or does anything go as long as all the numbers are within the excellent box?
So a 53 table with a 62.3 depth is still awesome?
Having read some I'm thinking that no, they all need to co-realte in a special way to be a good diamond, event though all the numbers are concidered exellent. But, I really have no clue, so please diamond experts, teach me!


Oh, and if therre are numbers that match better with other numbers, how should I be thinking when viewing a diamond, cause right now Im thinking table 55-57, but depth, not more thn 3steps away so 58-61. Dont know where i got that from, read something I cAnt find again so Im probably doing it wrong.

But also, crown and pavilin co relation, vest numbers together?

 

[proto]

Re: Table in relation do depth, crown in relation to pavilio

Combinations matter.

The guidelines on proportions and angles are only helpful to me to identify outliers and warning flag.

if you get images it kind of tells you everything you need to know other than seeing it in person.

If you are picking blind, the HCA checks the combinations For you so you dont need to memorise every combination

The issue with HCA is that it relies on the grading report dimensions being accurate and small changes like rounding errors can significantly affect the HCA value.

 

[LaSuecia]

Re: Table in relation do depth, crown in relation to pavilio

Ok, so thats what I thought.
I know the hca tool helps me with that, and ,wow, has that little tool helped me!
But Sometimes you get numbers like crown 33.5 and pavilion angle 41, and still the tool tells me its a 1.2 hca score, so those two numbers have to co relate in some way to make it a good score ( with the table/ depth nrs)
Still neither 33.5 or 41 are excellent and if I hadnt checked the tool Id probably leave that diamond alone.
Im really just curious about the formula, just geeky curious, Im somehow finding this whole world of diamonds very interesting and fascinating and want to learn more

 

[Karl_K]

Re: Table in relation do depth, crown in relation to pavilio

What the hca answers is does the crown/pavilion angle combo work with that table.
GIA rounding gives it more error than more accurate numbers.
You can enter the extremes of the GIA rounding to get a better idea at times.
The depth is to throw flags for possible over thin girdles.

There is nothing wrong with a 41 degree pavilion(some of my favorite combos have a 41 degree pavilion) with the right crown, table, and lowers.
Same with a 33.5 crown in come combos.
Both with the right other facet angles can get both ags0 and gia EX.

 

[LaSuecia]

Re: Table in relation do depth, crown in relation to pavilio

What the hca answers is does the crown/pavilion angle combo work with that table.
GIA rounding gives it more error than more accurate numbers.
You can enter the extremes of the GIA rounding to get a better idea at times.
The depth is to throw flags for possible over thin girdles.

There is nothing wrong with a 41 degree pavilion(some of my favorite combos have a 41 degree pavilion) with the right crown, table, and lowers.
Same with a 33.5 crown in come combos.
Both with the right other facet angles can get both ags0 and gia EX.

Ok, thanks you, I see, so basically, they have to "be a match" ,a good combo, and they dont nececerally ( tried spelling it three times, I give up) need to be excellent according to thr gia standard, but as long as they work together they can be geat too.

 

[Texas Leaguer]

Re: Table in relation do depth, crown in relation to pavilio

It's important to recognize too that a diamond with an AGS0 light performance based cut grade is unique in that it has been individually analyzed for the total combination and contribution of all its facets. That analysis involves sophisticated ray tracing and assessment of brightness, leakage,fire and contrast (as well as several other important attributes). It is not only a stricter standard than GIA EX, but it is the analysis of an accurate 3D model of the diamond itself and does not rely on rounded and averaged data. Having said that, it does not specifically grade optical precision so there are still some AGS0 that are better than others, despite the range being much tighter.

 

[LaSuecia]

Re: Table in relation do depth, crown in relation to pavilio

It's important to recognize too that a diamond with an AGS0 light performance based cut grade is unique in that it has been individually analyzed for the total combination and contribution of all its facets. That analysis involves sophisticated ray tracing and assessment of brightness, leakage,fire and contrast (as well as several other important attributes). It is not only a stricter standard than GIA EX, but it is the analysis of an accurate 3D model of the diamond itself and does not rely on rounded and averaged data. Having said that, it does not specifically grade optical precision so there are still some AGS0 that are better than others, despite the range being much tighter.

Ok,thanks,
I hve learned so much this week!

 

[diamondseeker2006]

Re: Table in relation do depth, crown in relation to pavilio

Going back to your first post, I'd narrow down those specs just a little. Plus, you need to be looking at pavilion angle and not pav depth.

table: 54-58

depth: 60-62.3

crown angle: 34-35.0

pavilion angle: 40.6-41.0

If you have a crown angle at 34, it may work better with a pav angle toward the higher end of that range, like 40.8-41.

Or if the crown angle is 35, it might work better with a lower pav angle of 40.6-40.8.

I will say that I once had a stone with 35 crown angle and 41 pav angle and it had a great idealscope image. So many combinations will work if you have light return images to verify. If you look at a lot of superideal cuts, you'll see most angles within these parameters.

 

[LaSuecia]

Re: Table in relation do depth, crown in relation to pavilio

Going back to your first post, I'd narrow down those specs just a little. Plus, you need to be looking at pavilion angle and not pav depth.

table: 54-58

depth: 60-62.3

crown angle: 34-35.0

pavilion angle: 40.6-41.0

If you have a crown angle at 34, it may work better with a pav angle toward the higher end of that range, like 40.8-41.

Or if the crown angle is 35, it might work better with a lower pav angle of 40.6-40.8.

I will say that I once had a stone with 35 crown angle and 41 pav angle and it had a great idealscope image. So many combinations will work if you have light return images to verify. If you look at a lot of superideal cuts, you'll see most angles within these parameters.

Very helpful, thank you!
Ive reserved this one at james allen, ( seriously concidering buying from abroad now)
Is it a keeper

http://www.jamesallen.com/loose-diamonds/round-cut/0.59-carat-i-color-vs2-clarity-ideal-cut-sku-328443

The crown and pavilion are within the narrowed down specs?

 

[tyty333]

Re: Table in relation do depth, crown in relation to pavilio

Yes, it is a keeper...AGS000 stone so it has ideal light return.

 

[diamondseeker2006]

Re: Table in relation do depth, crown in relation to pavilio

Very nice choice! If they are setting the stone, ask if they can place a prong on or near that inclusion near the edge.