so who says a 1ct diamond has to be 6.5x4mm????

[damo]

just wondering

 

[oldminer]

It does not have to be that diameter and depth. Most are deeper and less large in diameter. The measurements you gave in a round diamond generally would be a bit over 1.00ct, like 1.03ct by the standard formula.

There are many fancy shapes with very different dimensions that look very good.

 

[pricescope]

Damo,

1.0 ct Round diamond with Tolkowsky proportions (CrownAngle=34.5°, PavilionAngle=40.75°) and Medium Girdle should have diameter about:

6.48 mm at Table=53% and
6.50 mm at Table=57%

 

[damo]

so if I'm getting a 1.01 ct thats 6.37-6.43 x 3.96 what does that mean? its too small?
i dont know where the size is, the culet is none, girdle is thin to thick, depth 61.9% and table 58%
Any ideaS?

 

[Giangi]

But didn't you told me that the girdle isn't thick? Or am I out of my mind? (very possible

A thin to thick may be thick in 99% of places and thin in just a small part, especially if there's a natural or an extra facet. So this could explain the small diameter.

 

[Richard Sherwood]

-----------
so if I'm getting a 1.01 ct thats 6.37-6.43 x 3.96
what does that mean? its too small?
-----------

No, it's fine. The 61.9% depth falls in the top AGA Cut Class "1A" category, which ranges from 58.7 to 62.3%.

 

[damo]

Ahhh, thanks thats reassured me a bit. 0.05 of a mm ain't much to lose sleep over i guess.
I really like the stone which is the main thing, the fact that it was 6.37-6.43 rather than 6.5 bothered me slightly but that silly right?
Only thing is on check cert it has extremely thin to thick girdle, faceted. My dealer assures me this is ok.
What you say?
Thanks

 

[Richard Sherwood]

-----------
Only thing is on check cert it has extremely thin to thick girdle,
faceted. My dealer assures me this is ok.
-----------

Extremely thin is never OK, but it depends on how much of the girdle is extremely thin as to how much exposure you have to possible chipping.

The extremely thin portion of the girdle has no width to it. It is like the edge of a knife, and more susceptible to chipping. Usually though, extremely thin portions are very small, often because of a natural encroaching at that point, or possibly because the cutter remedied some sort of problem by taking the girdle down to the "edge".

Ask the dealer to show you with a loupe, scope or photograph where the extremely thin portion is, and see what you think.

You might also want to make the purchase contingent upon it meeting to your satisfaction after inspection by an independent appraiser. The appraiser will tell you if you have a problem or not.

 

[damo]

Thanks for advice, we're going to look at it with under a microscope tomorrow. He assure me its ok though? Should I be concerned? I do trust him. Maybe I shouldn't?

 

[damo]

also i dont understand how it can be extremely thin and faceted? to me a facet must mean an edge?

 

[damo]

we looked at the stone with a scope, the extremely thin part of the girdle is where there is a natural - the rest is med to thick.
he assures me this is ok - is that right?

 

[Richard Sherwood]

-----------
the extremely thin part of the girdle is where there
is a natural - the rest is med to thick.
he assures me this is ok - is that right?
-----------

With a repeat on the caution that an extremely thin portion of a girdle is never "OK", the fact that it is where a natural encroaches the girdle is usually better than if the girdle had been scalloped down to an extremely thin section.

The reason why is because with a natural creating the extremely thin section, it is usually a shorter length and at less of an angle than otherwise. Less of an angle means less of a "knife edge".

I would definitely get an independent opinion from a disinterested second party. Could be you're fine, could be you're not.

 

[Richard Sherwood]

-----------
also i dont understand how it can be extremely thin
and faceted? to me a facet must mean an edge?
-----------

A faceted girdle will be faceted all the way around except for where it's extremely thin.

 

[Richard Sherwood]

This first image shows scallops which have been taken all the way down to an "extremely thin" girdle range.

This is pretty extreme, in that you don't usually see girdles which are extremely thin all the way around, except possibly for some old european cuts.

 

[Rhino]

You're nuts if you don't get a professional 2nd opinion. A girdle graph would also be nice as it will show just how much of the girdle HAS that extremely thin portion to it. A disinterested 3rd party opinion is crucial in this type of case.

My .02c
Rhino

 

[Richard Sherwood]

This second image shows a "natural" encroaching on the girdle edge, leaving an "extremely thin" stretch between it and the girdle edge.

The thing about naturals is that their surface is often close to the angle of the girdle, which makes the extremely thin portion a blunter "knife edge", even though the extremely thin point is still as thin as that of a sharper "knife edge".

 

[Rhino]

Good illustration bro.

 

[Garry H (Cut Nut)]

In Rich's eg that stone would have a prong placed carefully over the thin spot and everyone lives happily ever after.

 

[damo]

thats what my dealer said, the prong will go over the natural and this is the only part thats extremely thin.
this will be ok?

 

[Richard Sherwood]

There's two possible scenarios. (1), you've got a setter who knows what he's doing, and he notches the prong properly so that it doesn't rest on the knife edge, and is stabilized against the diamond above and below.

In this scenario, the prong protects the knife edge portion of the girdle.

In the second scenario, the setter notches the prong improperly, and has the prong resting against the knife edge.

In this scenario, the first hard knock that prong takes will possibly result in a shallow chip running down from the girdle into the pavilion area. Sometimes they run all the way down to the culet.

There's a lot of setters about who don't have enough sense or expertise to do this correctly, so you want to make sure you've got somebody that knows what he's doing setting the stone. Discuss it with him or the manager beforehand, to see if they understand the concept.

 

[damo]

thats great advice, thanks, i'll make sure i mention that

 

[Mara]

Damo--I would definitely get a 2nd opinion either before you purchase the stone, or after the purchase within your return policy window. When making such a large purchase, it pays to be careful!! An extra $100 can set your mind at ease..find an independent appraiser in your area and have them look at the stone.

Best of luck!

 

[damo]

I've checked again, the ext thin portion is only where the natural is and i'm told is even less of a concern as the natural is on the bottom of the stone.
As far as the setter is concerned I've been assured he is a master craftsmen having previously been commissioned for the likes of cartier.

 

[damo]

Hi, thanks for all the advice, the stones being set and will be available for me to see next week.
What should I check before I part with my cash?
Thanks again