Proper Dimensions for the Proper Cut….. Please Help!!

[mishamish]

Hello All,

I''m getting very close to finally making my purchase, the only part that I’m still worried about is finding a proper cut through an online vendor. I know that cut is the most important C and i want to make sure that the diamond that i purchase will have that spectacular sparkle. The part that worries me is that without actually seeing the stone in person, all i have to go by is the dimensions provided by the dealer. Is there a true guide for proper cut dimensions? What should i be looking for in the following categories to assure that I’m getting something great:

Depth:

Table:

Crown angle:

Pavilion angle:

Girdle:

Polish and symmetry:

These are the only criteria for cut that I’m aware of. Are there other factors that i should be looking for?

Thank you in advance for all your help and insight!!!

 

[Lorelei]

Here are some numbers which have proved useful for some PSers to find a well cut stone, you can use these as a guide but remember some combos outside these ranges can work well too, use the HCA to see which have potential.

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!

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).

 

[neatfreak]

Here are some parameters to stay within, assuming we are talking round here right? An easy way to navigate too is to confine your search for AGS0 stones, which will pretty much always net you a great cut.

Note: the combos for crown and pavillion angles at the steeper and shallower ranges may need further examination.

depth - 60 - 62 ( although you can go deeper if all else is right, suggest a max of 62.6%)

table - 54 - 57%

crown angle -shallower 34 - 35% getting a bit steeper = further eval

pavillion angle - shallower 40.5 - 40.9 or 41 getting a bit steeper= further eval

girdle thin to slightly thick, medium, slightly thin are all fine, avoid extremes such as thin to ex thick.


ETA: Lorelei beat me to it, but also just wanted to add that you ALWAYS want to run these numbers into the HCA tool (under TOOLS) above and look for a score of 2 or below to make sure that all of your angles are working well together.

 

[mishamish]

Thank you for all the info!!

Just one follow up question in regards to the girdle, can you help me clarify some of the abbreviations I see online, ie: m-stk, tn-m, med-thk fac, m-tk, etc...

What do these abbreviations stand for and which ones should i avoid? It may be a dumb question, but i don''t want to take any chances in misreading the classification.

 

[Lorelei]

Date: 12/11/2008 10:37:03 AM
Author: mishamish

Thank you for all the info!!

Just one follow up question in regards to the girdle, can you help me clarify some of the abbreviations I see online, ie: m-stk, tn-m, med-thk fac, m-tk, etc...

What do these abbreviations stand for and which ones should i avoid? It may be a dumb question, but i don't want to take any chances in misreading the classification.

m- stk = medium to slightly thick ( good range)
tn - m = thin to medium ( good range)
med - thk fac = medium to thick, faceted
m - tk = medium to thick

The first two above are what to aim for and this info should help you,

http://diamonds.pricescope.com/girdle.asp

Also when you have some diamonds you are interested in, post the above info such as depth, table etc and any images such as Idealscope, then we can help you from there.

 

[mishamish]

Thanks Again!!!

 

[Lorelei]

Date: 12/11/2008 11:00:54 AM
Author: mishamish
Thanks Again!!!

My pleasure! Let us know if you need any more help!

 

[Regular Guy]

Mish,

It''s useful to know what trumps what.

Probably a good reader of reflector technologies could say their read of an ASET or IS would trump conceivably contradictory data presented with and AGS with zero light performance. The reverse could be true. Regardless, when in possession of a diamond with a grading report from AGS with a 0 light performance score, don''t bother to run the HCA.

Most places have a computer. Partner with your place of business (if you''re not shopping on line..then just do it yourself), to use the HCA, which uses most of your categories. This manages the relationships best. It does trump the packages of data suggested above.

When not available, the info above should help.

Push to partner with your vendor, though. It''s designed to be a win win. And, it''s your money.