crown angle info

[Lokis_mom]

Hi all, I need help in selecting a diamond. The size is 2.53, the CA is 32.5, PA is 41.6, the table is 58.
measurements are 8.78-8.83 X 5.39. Are these good dimensions?
I was also looking at another diamond, 2.66 ct, the CA is 36, PA is 40.6, table is 58, measurements 8.77-8.82 X 5.48

Thanks in advance!

 

[lovedogs]

Hi all, I need help in selecting a diamond. The size is 2.53, the CA is 32.5, PA is 41.6, the table is 58.
measurements are 8.78-8.83 X 5.39. Are these good dimensions?
I was also looking at another diamond, 2.66 ct, the CA is 36, PA is 40.6, table is 58, measurements 8.77-8.82 X 5.48

Thanks in advance!

Normally I would say to put it in the HCA calculator, but we can't if we don't have info about depth. What is the depth of both of them?

 

[Lokis_mom]

Thanks for reply, the depth of the 2.53 ct diamond is 61.2, and the depth of the 2.66 is 62.3. I was told that the 2.53 is a Tolkowsky standard cut grade.
Just nervous that the 2.53 diamond is too shallow, it's a big investment!

 

[Lokis_mom]

Normally I would say to put it in the HCA calculator, but we can't if we don't have info about depth. What is the depth of both of them?

I replied below, sorry, new to the forum!

 

[lovedogs]

That's weird , the HCA keeps giving me an error saying the numberw are invalid. Are you 100% sure of the values?

 

[Karl_K]

both are blah 41.6 is way to deep.
36-40.6 needs a smaller table

 

[Lokis_mom]

That's weird , the HCA keeps giving me an error saying the numberw are invalid. Are you 100% sure of the values?

yes, I figured it out, the 2.66 has HCA of 2, the 2.53 has an HCA of 3.8... Is 2 a good score?

 

[Lokis_mom]

both are blah 41.6 is way to deep.
36-40.6 needs a smaller table

Thanks for the input, but if you were to choose? the 2.53 or the 2.66?

 

[lovedogs]

Thanks for the input, but if you were to choose? the 2.53 or the 2.66?

I would choose neither and find a better stone. Sorry for being harsh but these aren't good choices. HCA is a rejection tool, and anything above 2 is a "no". If you tell us your budget them we can find something much better

 

[Lokis_mom]

I would choose neither and find a better stone. Sorry for being harsh but these aren't good choices. HCA is a rejection tool, and anything above 2 is a "no". If you tell us your budget them we can find something much better

thanks for your help!!

 

[Karl_K]

Thanks for the input, but if you were to choose? the 2.53 or the 2.66?

Hmmmm those are the only choices, a flat top(lower liveliness) with color entrapment or a stone with a high potential for lacking edge to edge brightness.
I would keep my money in the bank.

 

[Ss52]

Hmmmm those are the only choices, a flat top(lower liveliness) with color entrapment or a stone with a high potential for lacking edge to edge brightness.
I would keep my money in the bank.

KarlK, I’m very interested in your comment that the 2.66 could lack edge-to-edge brightness. Is it because of the 58% table? When you have time, could you elaborate a bit? Thank you.

 

[Karl_K]

KarlK, I’m very interested in your comment that the 2.66 could lack edge-to-edge brightness. Is it because of the 58% table? When you have time, could you elaborate a bit? Thank you.

58 table with a 36 crown has a very high chance of having over steep upper girdle facets. They are facets on the crown just in from the girdle.
When they get to steep the are darker in some lighting than the rest of the stone making it look smaller.
With a smaller table there is more room for them and they are are a less steep angle.
The crown geometry can be cut to compensate for this with shorter stars making the upper girdles longer and at a less steep angle but it very often isn't.

 

[kmoro]

58 table with a 36 crown has a very high chance of having over steep upper girdle facets. They are facets on the crown just in from the girdle.
When they get to steep the are darker in some lighting than the rest of the stone making it look smaller.
With a smaller table there is more room for them and they are are a less steep angle.
The crown geometry can be cut to compensate for this with shorter stars making the upper girdles longer and at a less steep angle but it very often isn't.

Hi Karl ...
I hope you don’t mind me asking .... does the table size necessarily affect the upper girdle facets? Would a smaller table not just be the result of a higher crown with the 36 crown angle? I have always thought of table size as related to crown height ? I can visualize how a lower crown angle and shorter stars would make the upper girdle facets less steep and longer, respectively ... but not how the table size would affect without a change in crown angle ... ???
(I really hope this isn’t another stupid day for me and I’m not completely being a potato here)

 

[Karl_K]

The stars and upper girdles have to fill the distance from the table to the girdle.
The 55 table gives it a longer distance to travel, so its at a shallower angle.
You can adjust the stars to lower the upper girdles but cutters pretty much stick with the 50%-55% range and don't.

 

[kmoro]

The stars and upper girdles have to fill the distance from the table to the girdle.
The 55 table gives it a longer distance to travel, so its at a shallower angle.
You can adjust the stars to lower the upper girdles but cutters pretty much stick with the 50%-55% range and don't.

Ahhh yes! I AM having another stupid day! Darnitt!!! Thanks for your patient explanation!!!
(I have been on morphine for pain and I can’t believe how much it affects my cognitive function!)

 

[Karl_K]

Ahhh yes! I AM having another stupid day! Darnitt!!! Thanks for your patient explanation!!!
(I have been on morphine for pain and I can’t believe how much it affects my cognitive function!)

It was a good question.
I feel for you, today is a bad day here too. Cold and damp and we didn't turn they heat back on so my joints are all locked up.
Feel better! Prayers outgoing.

 

[kmoro]

It was a good question.
I feel for you, today is a bad day here too. Cold and damp and we didn't turn they heat back on so my joints are all locked up.
Feel better! Prayers outgoing.

Thank you! Sorry to hear you are also suffering ... Sending healing wishes and prayers your way too!

 

[cj2be]

Sorry to hijack the thread but I have a question regarding something addressed here! When a diamond has over steep upper girdle facets, does that mean horizontally or vertically (or maybe even both)? I guess I’m just confused as to whether the determination is make based on looking at whether it’s light or dark or if there’s a more technical aspect to it

 

[cflutist]

34.5 and 40.8 is the combo I reach for, two of my CBI diamonds have these.
2.79 F-VS1
2.18 E-VS1