Find your diamond
Find your jewelry
shape
carat
color
clarity

GIA proportions

Status
Not open for further replies. Please create a new topic or request for this thread to be opened.

greta2002

Rough_Rock
Joined
Dec 17, 2002
Messages
22
I have an additional question. It seems as though many retailers describe the cut of a diamond as "ideal, premium, ..., fair, poor" based only on the table % and the total depth% for GIA certified diamonds. Is this a reasonable way to describe the cut? How can you ever know whether a GIA certified diamond is acutally cut properly (pavilion and crown depths, and angles not indicated on report)? Can you safely assume that a diamond within certain table % ranges and within certain total depth % ranges is "reasonably" well cut if certified by the GIA? Thanks again!
 

Garry H (Cut Nut)

Super_Ideal_Rock
Trade
Joined
Aug 15, 2000
Messages
16,019
No, no and no.
GIA has been researching for years to find a way to grade cut quality.
There is no basis for ideal, premium etc.
It is a bit like used cars.
That is why I have spent much time developing methods that are accessible to all (HCA and the Ideal-Scope).
hCA is hard to use with stones in stores and it is not easy to get crown and pavilion data. Ideal-Scope is hard to use on Internet stones, but easy to use in real B&M shopping :)
 

Richard Sherwood

Ideal_Rock
Joined
Sep 25, 2002
Messages
4,924
Although often a nice quality GIA certified diamond with a table size and depth within respectable ranges will often have an equally respectable cut, it is by no means certain.

You hit the nail on the head when you lamented the absence of pavilion depth / crown height and angles. These measurements are critical in order to get an idea if the cut is within the range you would like it to be. These measurements can be used as a "narrowing down" filter in your seach for the right diamond for you.

The thing to do is request a Sarin report on the diamond, or a gemologist's assessment of these critical figures. The AGS certificate (equal to the GIA certificate in stature) contains all this information. Many dealers are now augmenting GIA certs with Sarin proportion reports. Without these figures, you're flying in the dark with no instruments.

Rich, GG
Sarasota Gemological Laboratory
 

Richard Sherwood

Ideal_Rock
Joined
Sep 25, 2002
Messages
4,924
And yes, when you get down to the nitty-gritty of inspecting diamonds up-close and personal, I would highly recommend Garry's IdealScope. It takes the guesswork out of finding well cut stones for the layperson. For only $25, you have an instrument which might possibly give you hundreds or thousands of dollars better quality diamond for the money.

Rich, GG
Sarasota Gemological Laboratory

Hey Leonid, is it okay for one member to shamelessly promote another's product, or should I keep quiet about Garry's IdealScope?
 
Status
Not open for further replies. Please create a new topic or request for this thread to be opened.
Be a part of the community It's free, join today!
    March Birthstone 2021 - Aquamarine
    March Birthstone 2021 - Aquamarine
    Soapy Love
    Soapy Love
    How much to spend on an Engagement Ring in 2021
    How much to spend on an Engagement Ring in 2021

Need Something Special?

Get a quote from multiple trusted and vetted jewelers.

Holloway Cut Advisor



Diamond Eye Candy

Click to view full-size image.
Top