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Practicing PS know-how with PS diamond search function

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puravida

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Jsut trying to see if I''m getting the hang of the best RB stats.

I''m trying to do "practice searches" using PS''s "Search all" function for a Round H&A stone, 1 ct. ish.

In the search results, a page comes up with the listings and it reports the stone''s depth and table %.


Should I initially eliminate from consideration any stones that do not fall within:

depth - 60 - 62%
table - 54- 57%
?

(Numbers taken from other threads I''ve come across.)

After eliminating stones due to poor depth/table % would I then look at crown/pavillion angles?
 
Date: 12/19/2008 3:19:42 PM
Author:puravida
Jsut trying to see if I'm getting the hang of the best RB stats.

I'm trying to do 'practice searches' using PS's 'Search all' function for a Round H&A stone, 1 ct. ish.

In the search results, a page comes up with the listings and it reports the stone's depth and table %.


Should I initially eliminate from consideration any stones that do not fall within:

depth - 60 - 62%
table - 54- 57%
?

(Numbers taken from other threads I've come across.)

After eliminating stones due to poor depth/table % would I then look at crown/pavillion angles?


No as there can be configurations that still work well, and it depends on the quality of the diamond cut you are looking for. Here are some numbers you can use as a guide which should help you find a well cut stone but there can be proportions outside of these ranges which can still give you a lovely stone and can be subject to personal taste and preference - for example some prefer the look of a diamond with a 60% table. If you use the search by cut feature this will bring up most of the info you need on each diamond to include the HCA score. The crown and pavilion angles are very important as they are the engines which drive light return and ultimately give you the beauty of a diamond.

depth - 60 - 62% - although my personal preference is to allow up to 62.4%
table - 54- 57%
crown angle - 34- 35 degrees
pavilion angle - 40.6- 41 degrees
girdle - avoid extremes, look for thin to slightly thick, thin to medium etc
polish and symmetry - very good and above

note - with crown and pavilion angles at the shallower ends ( CA 34- PA 40.6) and steeper ( CA 35- PA 41) check to make sure these angles complement in that particular diamond - eyeballs, Idealscope, trusted vendor input - check as appropriate.

And from expert John Pollard.

As the above implies, configurations depend on each other. A little give here can still work with a little take there.

With that said, here's a "Cliff's Notes" for staying near Tolkowsky/ideal angles with GIA reports (their numbers are rounded): A crown angle of 34.0, 34.5 or 35.0 is usually safe with a 40.8 pavilion angle. If pavilion angle = 40.6 lean toward a 34.5-35.0 crown. If pavilion angle = 41 lean toward a 34.0-34.5 crown.



GIA "EX" in cut is great at its heart, but it ranges a bit wider than some people prefer, particularly in deep combinations (pavilion > 41 with crown > 35).

 
Thanks Lorelei. It was one of your responses that I actually pulled those numbers from
1.gif


Those ranges help but I''m still a bit confused as to how I should begin to eliminate not-so great stones right off the bat, that come up in a search, based on the depth/table/crown/pavillion numbers.

I guess the confusing part arises bc its not an exact set of numbers that will give you a good stone but there is a range of diff combos that will work.

I''m still a newbie trying to wrap my head around the numbers so I dont know how to look at a list of crown and pav angles and (or depth and table %, for that matter) and determine which combos would work, especially when they aren''t the ideal ranges or don''t fall within the ranges you posted above.

I''m still waiting for that aha!/lightbulb moment
33.gif
 
Date: 12/19/2008 3:34:39 PM
Author: puravida
Thanks Lorelei. It was one of your responses that I actually pulled those numbers from
1.gif


Those ranges help but I'm still a bit confused as to how I should begin to eliminate not-so great stones right off the bat, that come up in a search, based on the depth/table/crown/pavillion numbers.

I guess the confusing part arises bc its not an exact set of numbers that will give you a good stone but there is a range of diff combos that will work.

I'm still a newbie trying to wrap my head around the numbers so I dont know how to look at a list of crown and pav angles and (or depth and table %, for that matter) and determine which combos would work, especially when they aren't the ideal ranges or don't fall within the ranges you posted above.

I'm still waiting for that aha!/lightbulb moment
33.gif
No worries!

If you want to make it easier then you could search for just AGS0 cut grade diamonds using the search tool, and that should leave you with well cut stones to work from which have good numbers which should work well together. This is one way you can approach this. However this is limiting in as much that there are well cut GIA graded diamonds out there that might fit the bill depending on what you are looking for which will be excluded.


Alternatively, if you use the cut quality search, then that will have most of the info you need listed. You will see the HCA score if that makes things easier to the left when you use this search, the aim is to score 2 or below then evaluate from there, so that might be another way to proceed as you can see these scores at a glance, then you can assume that these diamonds are worth further investigation and that the angles etc are in a range which is worth further evaluation, as the HCA will narrow things down for you as it is intended to be used, as an elimination tool.

And yes you are right that there are a range of combos which will work, again the HCA will help you know which combos could work and which ones won't.
 
35.gif
 
Lorelei: that''s a good idea, starting with the HCA scores. at least it gives me something to start with to initiate some knod of process of elimination.

Regular guy: thanks, i hadn''t come across those threads yet.
 
Date: 12/19/2008 4:05:45 PM
Author: puravida
Lorelei: that''s a good idea, starting with the HCA scores. at least it gives me something to start with to initiate some knod of process of elimination.

Regular guy: thanks, i hadn''t come across those threads yet.
Glad to help! If you start with the cut quality search option, all the info is there for you and also the HCA really comes into its own in eliminating the lesser performers as it was created to do. Plus Ira''s links can help!
 
As a prcatice example, I put a 1 ct., H&A, G, SI1, into the Cut Quality search and came up with one stone:

http://www.jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-1193887.asp?b=16&a=12&c=77&cid=131

depth 61.2%
table 55.8%

pol/sym both ideal

girdle: thin to med

Crown Angle: 34.1°
Crown %: 15.00
pavilion Angle: 41.0°
pavilion %: 43.30


All ranges look good according to the ranges you posted. (I guess they should considering the type of search I did.)

IS image looks a bit blurry so hard for me to "practice" evaluate.

The AGS report indicates some feathers? that look like they would be visible from the top. But this might not be necessarily so, right? I''d have to ask for an "eyeclean" verification?

Stone should be a good performer, right?

The Cut Quality search is a great tool for ppl like me who can''t wrap their heads around the numbers required for a great stone. It does the work for me. But if I''m looking at a stone that''s not in that database (like a stone from a local jeweller) then it ain''t so easy!
 
Date: 12/19/2008 4:25:11 PM
Author: puravida
As a prcatice example, I put a 1 ct., H&A, G, SI1, into the Cut Quality search and came up with one stone:

http://www.jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-1193887.asp?b=16&a=12&c=77&cid=131

depth 61.2%
table 55.8%

pol/sym both ideal

girdle: thin to med

Crown Angle: 34.1°
Crown %: 15.00
pavilion Angle: 41.0°
pavilion %: 43.30


All ranges look good according to the ranges you posted. (I guess they should considering the type of search I did.)

IS image looks a bit blurry so hard for me to 'practice' evaluate.

The AGS report indicates some feathers? that look like they would be visible from the top. But this might not be necessarily so, right? I'd have to ask for an 'eyeclean' verification?

Stone should be a good performer, right?

The Cut Quality search is a great tool for ppl like me who can't wrap their heads around the numbers required for a great stone. It does the work for me. But if I'm looking at a stone that's not in that database (like a stone from a local jeweller) then it ain't so easy!
Thats it, you have got it!!! Great diamond, AGS0, good numbers etc, good proposition. And yes you always need to check with the vendor if a diamond is eyeclean to your standards, you can't tell by photos or a grading report.

And with virtual diamonds in the database it does take more work weeding those out with the HCA and you need depth table and angles to be able to do so if listed. But for the type of diamond you are looking for, I would stick to in house diamonds you can find with the search by cut tool.

Glad to have helped!
 
Date: 12/19/2008 4:25:11 PM
Author: puravida
But if I''m looking at a stone that''s not in that database (like a stone from a local jeweller) then it ain''t so easy!
So, maybe using both HCA and investing in your own $25 IS would be good!

Try having your vendor fire up their computer for you, btw. If you''ll use it to vett your options...why not get their cooperation to do it on the spot!
 
Date: 12/19/2008 5:00:03 PM
Author: Regular Guy

Date: 12/19/2008 4:25:11 PM
Author: puravida
But if I''m looking at a stone that''s not in that database (like a stone from a local jeweller) then it ain''t so easy!
So, maybe using both HCA and investing in your own $25 IS would be good!

Try having your vendor fire up their computer for you, btw. If you''ll use it to vett your options...why not get their cooperation to do it on the spot!
Ditto Ira, that way you can run your contenders through the HCA on the spot!!

And here is a link where you can purchase an Idealscope -

http://www.ideal-scope.com/cart_zoom_item.asp?Id=2&ShowAdd=Y
 
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