ECs: Must the table always be smaller than the depth?

[ErikaFlute]

Hello

Thanks for all your advice and suggestions in recent posts.
I''m looking for an EC diamond and (as I''m sure you all know) there is a lot of choice, inlcuding plenty of bad stones available. I''m trying to be as specific as possible in my serach criteria in order to save time.

So. With that in mind I have a very general question for those with knowledge & experience...

1) Is it correct to only consider EC diamonds where the table is smaller than the depth?

OR to put it another way...

2) What is the effect on the diamond when the table is bigger than the depth?

Please find an example attached.

Erika

 

[chrono]

In short, when the table is greater than the total depth, there is a high chance of the crown height to be low, thereby causing a glassy appearance. Most people do not like this look but a very few do. In order for the EC to be fiery aka give off large flashes of coloured light, one of the criteria is a high crown height and a very small table. Sometimes, the table and depth are very close but the table is slightly higher than the depth yet the stone performs. This is due to all the other angles being cut just right. For example, a table can be 65% with a depth of 64% and still be a stunning EC if the other angles are a good combination. It is no guarantee that a smaller table than depth is going to be a winner but your chances are better than if it’s the other way around.

 

[bgray]

I purchased an EC a few years back after much "research." I believe that the generally, but not always, the structure of the diamond crystal (drives how its cut) is such that when cut so that the depth is greater than the table the higher crown is more likely to result. Again -often when the table is bigger than the depth the crown is more likely to be fairly low. I have a stone with a depth of 62.5 and a table of 62 with a crown height of 11.2 (ish--i cant recall the exact percent.) As you may have realized ECs are often deep and so look smaller than their carat weight. I really wanted a stone with maximal size but still optimal cut quality--no easy feat. Mine isnt perfect but its pretty good.

 

[Lorelei]

Hi Erika

Some EC's with larger tables can be beautiful stones depending on the overall cut quality and proportioning, but generally a table which is considerably larger than the depth can make the diamond look glassy and result in a shallow crown height which can mean not much fire. But images are essential in order to judge these shapes properly and to include the patterning.

Here are a few guidelines;

depth 70% or less
table 65% or less
crown height 10% and above

Then the rest is images, ASET and detailed photos preferably as you can't tell much by numbers.

 

[emeraldlover1]

Date: 12/16/2009 9:01:19 AM
Author: bgray
I purchased an EC a few years back after much ''research.'' I believe that the generally, but not always, the structure of the diamond crystal (drives how its cut) is such that when cut so that the depth is greater than the table the higher crown is more likely to result. Again -often when the table is bigger than the depth the crown is more likely to be fairly low. I have a stone with a depth of 62.5 and a table of 62 with a crown height of 11.2 (ish--i cant recall the exact percent.) As you may have realized ECs are often deep and so look smaller than their carat weight. I really wanted a stone with maximal size but still optimal cut quality--no easy feat. Mine isnt perfect but its pretty good.

Ditto everyone on the glassy appearance. It''s a presumption based on the proportion and not having the crown height or seeing it in person.

@bgray....do you have pictures? You mention your stone a lot and I don''t think I''ve actually ever seen it. It''s possible that I''ve missed it but I would love to see your stone.

 

[ErikaFlute]

Hi thanks for the comments.

To flip it the other way round...

How about a stone where the table is MUCH smaller than the depth?

I''ve found a diamond where the table is 60% but the depth is 69.2%

What effect might I expect with this stone?

Thanks, Erika

 

[bgray]

possibly superbly brilliant and firey

 

[chrono]

It only tells me that this EC might be worth calling in to get further testing (ASET) and a magnified picture of the stone face up (table view) to look at the step cutting. However, the Scrooge in me doesn’t like ECs with a depth close to the 70% range because it will face up smaller than an EC with a 65% depth. It may not be much to others but I like to maximize the size of my stone.

 

[ErikaFlute]

Okay. Well that would be lovely!

It''s not the case that a depth of 69.2% would "face-up" smaller?

It''s a 1.23 carat, 5mm by 7mm

 

[ErikaFlute]

Ah thanks, I must have written that reply at the exact same time as you. Seems as though I was on the right track!

 

[bgray]

Date: 12/16/2009 9:57:17 AM
Author: Chrono
It only tells me that this EC might be worth calling in to get further testing (ASET) and a magnified picture of the stone face up (table view) to look at the step cutting. However, the Scrooge in me doesn’t like ECs with a depth close to the 70% range because it will face up smaller than an EC with a 65% depth. It may not be much to others but I like to maximize the size of my stone.

a big ditto! my response was to its possible appearance...

 

[Lorelei]

Date: 12/16/2009 10:00:41 AM
Author: ErikaFlute
Okay. Well that would be lovely!

It's not the case that a depth of 69.2% would 'face-up' smaller?

It's a 1.23 carat, 5mm by 7mm

Depth doesn't always relate to spread in fancy shapes in the same way that it does in round diamonds, as long as you stick to 70% or below ( and expert on these shapes Karl K goes by this guideline) you should be fine and look at the diameter in MM to ascertain face up size. These shapes can be more complex concerning weight retention as there are other areas rather than the physical depth where weight can hide. If you can get images for the above diamonds it would be really helpful as again numbers do not tell you much at all. What is the exact measurement, for example 7.26 by 5.31mm?