I don't have a fancy trig calculator. Can someone help me with %ages?

[Starfacet]

I have seen formulas for calculating crown and pavilion angles from percentages, but I get lost after "get out your trig calculator."

Can anyone tell me what the crown and pavilion angles would be for the following percentages?:

Crown 9.5%
Pavilion 44.5%

I notice HCA only lets you put in angles.

Thanks in advance for any help!

 

[OoohShiny]

This thread has popped up in the 'Related topics' section above this post, which may be of use.

https://www.pricescope.com/community/threads/percentages-to-angles-using-trig-calculator.13404/

Many thanks to @oldminer for posting it originally.


I would add that if it's a round, 9.5% crown is very low...

 

[Karl_K]

Need to know the table and culet size.

 

[Karl_K]

RB only.
For a pointed culet 44.5 is 41.67 degrees
9.5% is really low.
HCA is going to be high ~4+

 

[Garry H (Cut Nut)]

That % data os worse than usless because of rounding. Dont even try. Get angles. And then the rounding is still bad.

 

[Starfacet]

Need to know the table and culet size.

Table is 61%
Culet is listed as Very Small.
This info might not help much. And yes, it's for an RB. Thanks!

 

[Karl_K]

25.98
41.74

As Garry said that could be off by some unknown margin.

 

[Starfacet]

Thanks!

 

[Sparkles88]

Hi OP, I hope you don’t mind me adding to thread rather than posting a new thread.

Can someone please help me work out angles so I can work out the HCA score? My diamond was purchased over a decade ago, pre PS and is certified by HRD. I’ve noticed that HRD certifies my diamond as Very Good, so I’m not expecting it to be a rated well for light performance. Would my diamond be a candidate for a re cut?

 

[Karl_K]

33
40.7

Those are good numbers for a 60/60 style stone even considering some rounding.

The inclusions would be the major factor in a recut.
They may interfere with a recut or turn into an I1 with the inclusions in a different part of the stone and the stone smaller. si2 diamonds can be tricky for recutting but the only way to know for sure is have it evaluated in person
Proportion wise it could likely be recut well above 2ct.

 

[Sparkles88]

33
40.7

Those are good numbers for a 60/60 style stone even considering some rounding.

Thank you so much Karl, I had suspected I had a 60/60 stone as my diamond is quite sparkly but doesn’t exhibit much fire. With the dimensions of my diamond, would be it suitable for a recut?

 

[Karl_K]

See my post above, sorry I didn't see the recut question until after and edited my post and we cross posted.

 

[Sparkles88]

33
40.7

Those are good numbers for a 60/60 style stone even considering some rounding.

The inclusions would be the major factor in a recut.
They may interfere with a recut or turn into an I1 with the inclusions in a different part of the stone and the stone smaller. si2 diamonds can be tricky for recutting but the only way to know for sure is have it evaluated in person
Proportion wise it could likely be recut well above 2ct.

Thanks Karl for your insights, something to consider for sure.

 

[Shelby1975]

Hi OP, I hope you don’t mind me adding to thread rather than posting a new thread.

Can someone please help me work out angles so I can work out the HCA score? My diamond was purchased over a decade ago, pre PS and is certified by HRD. I’ve noticed that HRD certifies my diamond as Very Good, so I’m not expecting it to be a rated well for light performance. Would my diamond be a candidate for a re cut?

Hi Sparkles88 - I hope you don't mind me contacting you via this thread. I saw your other post in another thread commenting that you're looking for studs and you're in Oz? I'm in Sydney and have a pair of OMC studs if you're interested. Again, so sorry if I have done the wrong thing by writing this here. Thanks!

 

[Sparkles88]

Hi Sparkles88 - I hope you don't mind me contacting you via this thread. I saw your other post in another thread commenting that you're looking for studs and you're in Oz? I'm in Sydney and have a pair of OMC studs if you're interested. Again, so sorry if I have done the wrong thing by writing this here. Thanks!

No problem at all contacting me here. Ive seen your beautiful studs listed and sadly they are out of my price range and I was looking for MRB pair. I hope you find a buyer soon that will cherish them.