please help...conflicting ''ideal cut'' proportions

[deggles]

Hello,

I''ve done a decent amount of research and now I''m ready to go out and shop for a loose stone. I''m looking for a very high quality 1ct stone. However, I have found conflicting ''ideal cut'' proportions depending on the source.

bluenile.com says that an ideal cut has the following dimensions:

Depth: 60.1-61.9
Table: 55-57

The AGS ideal cut has different depth and Table:

Depth: 59.3
Table: 53

Which do I trust and why is there such a big difference in Table dimensions between two ''trusted'' sources.

Thanks for the help,

deggles

 

[cascadejim]

Always go with the proportions of a grading lab over a vendor. AGS is the top tier from my understanding so if it says it''s ideal, it''s the most ideal diamond you can buy compared to other labs.

 

[codex57]

Unfortunately, there''s no real "standard" in anything. Even GIA (which is as close to one of the standard makers as you can get) uses a set of master stones and then the graders grade by eye according to which stone it matches up closest with.

Basically, there''s a ton of judgment calls in the diamond biz. It kinda boils down to who you trust and what your acceptable parameters are. Even the "ideal" cut is subject to interpretation b/c cutting it a certain way emphasizes certain qualities and some people prefer one quality over another. See the different Heart and Arrow companies for a bunch of differences on those "ideal" cut stones.

 

[valeria101]

Well, Blue Nile doesn''t explain why they call "ideal" ideal, and AGS is about to change their ideal standard as well. GIA will have one too! So does EGL, HRD, AGA and others. Does it help that each dimaond seller has it''s own top selection that may or may not agree with one "ideal" or the next !???

Sorry... this is it though. Comparing the boundaries of these standards may not lead very far: these are more or less narrow and accordingly expensive, but no issuer of "ideal" standards explains why they made the cut where it stands now. Just look what criticism the up-comming GIA grades got! (PS article on front page).

Now, obviously I am not a big fan of comparing numbers blidly. These overlapping or conflicting standards try to describe the same thing - how a diamond looks - but stop short of it I am affraid.

 

[aljdewey]

Date: 1/11/2005 1:59:44 PM
Author:deggles

The AGS ideal cut has different depth and Table:

Depth: 59.3
Table: 53

Which do I trust and why is there such a big difference in Table dimensions between two ''trusted'' sources.

Hi, Daniel: I don''t know what your source is for the AGS figures you''ve quoted above, but they aren''t correct.

I''ve attached a table that shows the tolerances for an AGS0 "ideal" cut.....as you can see, the table can range from 52.4 to 57.5%.....

Which do you trust? Trust this graph from the AGS....they are the premier lab that grades cut.

 

[deggles]

Thank you aljdewey. That diagram is exactly what I was looking for. You were correct, the measurments I provided weren''t AGS, they were actually Tolkowsky Ideal Proportions, a little different from the AGS diagram.

Do you know if the Halloway Cut Adviser is based on the AGS cut standards?

Thanks Again,

deggles

 

[Garry H (Cut Nut)]

1. Blue Nile drop ship so they do not know the interrelationship of crown and pavilion angles. They have used the available data to select diamonds that "probably" or "possibly" have ideal cut proportions. Use an appraiser.
2. AGS ieal includes many non-ideal stones - that is why they are changing to a better system next year.
3. AGS will look more like HCA except i accept more shallow proportions than AGS (although shallow stones are very rare)

 

[noobie]

Date: 1/11/2005 2:26:21 PM
Author: valeria101
Well, Blue Nile doesn''t explain why they call ''ideal'' ideal,

Blue Nile classifies their stones as ideal by depth and table ranges, at least that''s what they told me. You need to get sarin data to get more details