12 replies to this topic

[funsfamily]

What's ideal cut? seriously, how do you distinguish the cut by looking at them inside the jewelry store.

Does H&A means ideal cut?
Does excellent symmetry and polish means ideal cut?
or
the Table and Depth % determine an ideal cut or not?

what if the jeweler tells you that a diamond is ideal cut, how could you tell if that's true or not?

thank you very much

[denverappraiser]

What's ideal cut?
"Ideal' is a set of parameters that someone has defined as such. Not all dealers use the same definitions. If someone uses this term, ask them what they mean by it

Most dealers are using the old AGS definitions:
Table: 53-57%
Crown Angle: 34-35.5 degrees
Girdle: Thin, medium or slightly thick
Pavilion Depth: 42.5-43.5%
Culet: None, very small, small, medium.
Symmetry: Excellent
Polish: Excellent

seriously, how do you distinguish the cut by looking at them inside the jewelry store.
Check the paperwork if the ideal term is an important feature for you. It will have either a Sarin report or an AGS lab report. Most labs, including GIA, don't use this term and AGS only includes it on some of thier types of reports. Most lab reports don't include enough of the data for you to figure it out for yourself if they are using the above definition. There are other reports and tools that people use to try and communicate the cut quality of a stone as well including Brilliancescope, ISEE2, and ASET for example and they have their own ways of describing things.

Does H&A means ideal cut?
No

Does excellent symmetry and polish means ideal cut?
No

or the Table and Depth % determine an ideal cut or not?
No

what if the jeweler tells you that a diamond is ideal cut, how could you tell if that's true or not?
Choose a jeweler that you otherwise have some reason to trust. Ask them what they mean by their use of the term. Check the raw data against their conclusions. If you don't have access to the raw data, find an independent appraiser who can assist you with it.

thank you very much

Your welcome.

Neil Beaty
GG(GIA) ISA NAJA

[10X]

What's ideal cut? seriously, how do you distinguish the cut by looking at them inside the jewelry store.

Ideal is a grade given by the AGS when the diamond has perfect polish, symmetry and proportions (table, crown angle, pav. angle, etc.). The new AGS cut grading system also takes performance into consideration when assigning an Ideal grade.

Because AGS is the only lab that uses the term 'Ideal', most Ideal diamonds are graded by the AGSL. This does not mean that other stones can't be Ideal. If you are considering a GIA graded stone, you would need additional cut information provided by technologies such as Sarin or OGI to know whether or not the diamonds falls with the Ideal proportion parameters.

The most important evaluation is your eyes. If you are comparing stones in person, you want to look for the most brilliant diamond in various lighting conditions. Hallogen lights will make most diamonds appear more brilliant so beware of this as it is not a natural lighting condition.

Does H&A means ideal cut?

Not all Ideal cuts are Hearts and Arrows and not all Hearts and Arrows are Ideal cuts.


Perfect proportions coupled with perfect symmetry produce the beautiful Hearts & Arrows effect of these Super Ideal Cut diamonds. The AGSL grades symmetry according to where the facet junctions meet. This does not take into consideration the differences between facet angles or the relative ratios of the different facets. This explains why Ideal Cuts can lack Hearts & Arrows patterns.


Does excellent symmetry and polish means ideal cut?
or the Table and Depth % determine an ideal cut or not?

An Ideal cut takes into consideration perfect polish, symmetry and proportions. Proportions and symmetry are most directly related to a stones performance.

what if the jeweler tells you that a diamond is ideal cut, how could you tell if that's true or not?

Ask them if they have a certficate for the stone stating that it is Ideal. Or if it is a GIA certificate(EX/EX), if they have additional documentation regarding the diamonds proportions.

[ben]

Quote

Because AGS is the only lab that uses the term 'Ideal',

But there sure are a whole lot of retailers that use the word "ideal". It gets confusing out there. And really, there is no such thing as a singular specification that describes an ideal diamond. According to recent research by GIA, diamonds can have a fairly wide range of parameters and still have amazing light return characteristics.

[barry]

Ben hits on an important point; i.e.; there are more definitions of ideal cut being pushed by vendors than you can shake a stick at.

For consumers it is very confusing.

To me, the definition of "Ideal Cut" encompasses not only external factors such as Polish, Symmetry, Towlkowsky's classical definition which went by strict "numbers" guidelines, and a crisp H&A pattern, but also, most importantly, that of optical symmetry or light performance as measured by the Gemex Brilliancescope.

This is a key factor. Towlkowsky's mathematical calculations postulated and showed that certain "numbers" resulted in a more beautiful diamond. Depending on the cutter's correct alignment of facets, optimizing that visual beauty may not always be the result. Measurements of optical performance definitively show whether a diamond has the sparkle and brilliance that will be "seen" and is a factor that IMO, must be factored into the consumers decision making process.

When people look at her ring nobody will be able to tell you the "numbers" on the diamond, but they sure will be able to tell whether it snaps, crackles, and pops with light. Light performance is what you want and what you're buying.

Take a look at the attached graphic. A GIA EX-EX that has sweet "numbers" but with mediocre light performance.

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[barry]

And now take a look at this diamond that we recently sold from our Diamond Specials section.

By the "numbers" this comes in as an AGS-1 cut with "only" Good Polish and Good Symmetry. Definitely NOT an "Ideal Cut" by any measurement any jeweler wants to use.

But look at this diamonds light performance. Outstanding and guaranteed that this stone will be seen.

Facet size, facet angle, and facet alignment are on the money.

If you go by the "numbers" alone you very well could be missing out on a fantastic diamond.

Light performance is the key.

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[funsfamily]

THANK YOU SO MUCH EVERYONE for all of your input.

the more I read on this forum, the more study i need to do ...........ohh well, here is my question, given the sarin and GIA certification datas, how do you determine the light return preformance?

Are there any online tools I could use to compare diamonds?

I actually tried the diamond calculator but it required a license............

thank you very much!!!

[barry]

Light performance is measured by a machine designed for that purpose.

Sarin gives you the Cut specs of the diamond and the GIA report gives you the external measurements, Polish, Symmetry, Fluorescence, etc.

[funsfamily]

I guess copies of ideal scope images could reflect the light performance of the diamond, right?

[10X]

The IdealScope was originally developed for brilliance assessment. The red areas are an indication of how much light refracts back from the diamond. White areas indicate light leakage. Note, all diamonds have some amount of light leakage. In Ideal cuts its usually represented as tiny white wedges around the edges of IdealScope images.

The IdealScope does not however, quantify the amount of brilliance, fire and scintillation like other technologies do.

[funsfamily]

other than those scope images , there is no other ways to tell the light performance other than looking at in person (with a microscope i guess)? please advise

[barry]

The eyes are the best way, of course. Otherwise, the Brilliancescope is an excellent assessment tool.

[barry]

Bump. Einstein's Theory of Relativity.