New GIA and AGSL Naming Conventions For Cushion Cut Diamonds

[coati]

New Consumer Article by ChunkyCushionLover

https://www.pricescope.com/journal/new_gia_and_agsl_naming_conventions_cushion_cut_diamonds

Thank you for your contribution.

 

[Garry H (Cut Nut)]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Thanks CCL.
I have passed it on to other professionals and lab directors who thank you too.
Very professional and thorough!

 

[John P]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Thank you for the time and effort invested here Jordan.

The inclusion plots printed on GIA reports are not scans of the actual diamond and may differ from the actual facet structure particularly in the shape and relative proportions of the pavilion facets.

I'm glad you'd covered this so well. When people (pros and consumers alike) are accustomed to the greater detail & specificity on RB reports this point is thorny to explain. I hope, as scan technology improves, the practice will be revisited.

AGS does not use the traditional term Old Mine Brilliant and will only use the term Old Mine Cut on their grading reports if the appearance truly fits that of an older cut stone from the appropriate time period.

In terms of the hoped-for compatibility you mentioned; do you know if AGSL is matching GIA's three-out-of-four criteria for Old Mine Brilliant when they classify a diamond as an Old Mine Cut?

 

[ChunkyCushionLover]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Thank you for the time and effort invested here Jordan.

The inclusion plots printed on GIA reports are not scans of the actual diamond and may differ from the actual facet structure particularly in the shape and relative proportions of the pavilion facets.

I'm glad you'd covered this so well. When people (pros and consumers alike) are accustomed to the greater detail & specificity on RB reports this point is thorny to explain. I hope, as scan technology improves, the practice will be revisited.

Thanks Sir John I appreciate the feedback. It is worth repeating that GIA intends only to show the size, shape, and location of inclusions in their plots. They never intended their inclusion plot diagrams to be used for the indentificaton of structure, or the relative proportions of the facets.

In contrast AGS uses a 3D scan, unfortunately due to scan error this is not enough for the plots on their reports. By viewing the scan they still have to generate from scratch a template in Gemcad which can then be used to fit the scan data to generate a plot. I applaud them for undertaking this time consuming process as it helps differentiate stones with the same outline shape, but differing relative proportions of the crown and/or pavilion facets.

AGS does not use the traditional term Old Mine Brilliant and will only use the term Old Mine Cut on their grading reports if the appearance truly fits that of an older cut stone from the appropriate time period.

In terms of the hoped-for compatibility you mentioned; do you know if AGSL is matching GIA's three-out-of-four criteria for Old Mine Brilliant when they classify a diamond as an Old Mine Cut?

If the AGSL were to consider the shape and style of an antique they would take into consideration GIA's criteria and then make a judgement call on whether the stone truly looks like an old stone. Modern reproductions of the Old Mine Cut style that contain a Cushion outline would still be described as Cushion Brilliant.

For the benfit of readers of this forum it is worth mentioning that Old Mine Cuts were not restricted to only Cushion or Square shapes. In the full description of both shape and style, Old Mine Cut by itself would not be sufficient as a full description as is often used by trade.

 

[ChunkyCushionLover]

Quick Reference Chart

Thank-you to David Atlas who made the prudent suggestion that I include a quick reference chart.
While not exhaustive this chart represents the most common facet structures with cushion outlines and how both labs would describe them.

 

[missydebby]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Just freeken awesome. Thanks CCL

 

[John P]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Thanks for the reference chart.

Something came up that’s probably worth mentioning: You used AGSL (meaning the AGS lab) in the article, but not GIA Laboratory. As a point of note the elder statesmen at GIA refer separately to GIA (education) versus GIA Laboratory. I bring this up because GIA education continues to teach about various old shapes and uses a variety of names for them, whereas GIA Laboratories made the decision to follow the simplified naming conventions you have presented. It may be useful to make it clear for current students that what you presented is, in fact, in harmony with GIA Laboratory even if it differs a bit from what’s taught in class.

 

[ChunkyCushionLover]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Thanks for the reference chart.

Something came up that’s probably worth mentioning: You used AGSL (meaning the AGS lab) in the article, but not GIA Laboratory. As a point of note the elder statesmen at GIA refer separately to GIA (education) versus GIA Laboratory. I bring this up because GIA education continues to teach about various old shapes and uses a variety of names for them, whereas GIA Laboratories made the decision to follow the simplified naming conventions you have presented. It may be useful to make it clear for current students that what you presented is, in fact, in harmony with GIA Laboratory even if it differs a bit from what’s taught in class.

Thanks John, that is an interesting point. I will have to get further guidance on this from GIA and will respond once I have a comprehensive understanding of what is being taught.

 

[Judah Gutwein]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Well done.
Thanks.

 

[grantmcgrath]

Re: New GIA and AGSL Naming Conventions For Cushion Cut Diam

Hi there,
Just wondering whether all cushion cut diamonds with a "crushed ice" internal appearance would be classed as cushion modified cuts after these naming conventions changed. I have a GIA certificate from 2007 before the classifications changed and a diamond with a crushed ice appearance, but the certificate states that it is a cushion brilliant cut - not modified...
Thanks