Does 34.5 crown angle go well with 45% star and 75% LGF?

[icycherry]

Hi guys,

I've got a diamond produced in Canada, which has very good figures (at least to the eyes of a newbie): 61.9%depth; 55%table; 34.5crown angle and 40.8pavilion. What bothered me was the star and lower half, which was 45% and 75%. Would this combo affect the fire (which I highly care) and brilliance of the stone? I have heard that if the star is smaller, it should go with a steeper crown. It seems that 34.5 is not steep enough. Appreciate any opinions!

 

[icycherry]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

waiting for help.....

 

[yssie]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Post the exact carat weight and report number and specify which authority issued the report.

You are asking about nitpicky nuances and we don't have enough info to nitpick with.

 

[John P]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Per Yssie: On its face 55-408-345-45-75 is not an issue. But it depends on how specific you want to get.

Impossible to say more because, aside from table, the data points are averages of 8-16 separate measurements apiece. Those averages are further rounded up-or-down if it's a GIA report. From this data there's no way to know how consistent the cutting is facet-by-facet, if that is important to you.

 

[yssie]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Per Yssie: On its face 55-408-345-45-75 is not an issue. But it depends on how specific you want to get.

Impossible to say more because, aside from table, the data points are averages of 8-16 separate measurements apiece. Those averages are further rounded up-or-down if it's a GIA report. From this data there's no way to know how consistent the cutting is facet-by-facet, if that is important to you.

From the mouths of experts

 

[icycherry]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Post the exact carat weight and report number and specify which authority issued the report.

You are asking about nitpicky nuances and we don't have enough info to nitpick with.

Here are the more detailed figures of this stone:

1.72carat; measurements: 7.69-7.71*4.76; Depth: 61.9%; Table: 55%; Crown Angle: 34.5°; Crown Height: 15.5%; Pavilion Angle: 40.8; Pavilion Depth: 43.0%; Star Length: 45%; Lower Half: 75%; Girdle: Medium, Faceted (3.5%); Culet: None

The report is issued by GIA.(That might be a grerat problem 'cause the figures are rounded ones, not accurate enough) I understand that it would be uneasy to tell exactly how this would affect the performance of the stone just by figures, but I really have no way to see the stone before I pay for it. So....still want to hear some opinions, even conjecture would be greatly appreciated.

 

[yssie]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Here's a tutorial from Good Old Gold that introduces LGF and star: http://www.goodoldgold.com/Articles/MinorFacets/

The numbers are what the PS community would call "safe" - worth further investigation. But what you're asking... well, garbage in, garbage out! GIA rounds star and lgf to 5%, crown to 0.5deg, pav up to 0.2deg, and the numbers printed on the report are averaged around several sections of the stone as Mr. Pollard said...

And to add to those uncertainties are other errors: the Sarin scanners GIA uses in the labs are listed (on the Sarin webpage) as accurate to +/- 0.1deg, the GIA report tells us nothing about optical symmetry (the symmetry of the reflections of facets you see when you look into the stone - it's a function of facet meet symmetry but there are other parameters)...

IMO your best friend in this situation is an idiot-proof return policy. Or buying from a boutique vendor who specialises in exactly this sort of nitpicking - GOG, WF, BGD, Infinity (sold by HPD) are the first PS favourites who come to mind.

 

[Dancing Fire]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Post the exact carat weight and report number and specify which authority issued the report.

You are asking about nitpicky nuances and we don't have enough info to nitpick with.

Here are the more detailed figures of this stone:

1.72carat; measurements: 7.69-7.71*4.76; Depth: 61.9%; Table: 55%; Crown Angle: 34.5°; Crown Height: 15.5%; Pavilion Angle: 40.8; Pavilion Depth: 43.0%; Star Length: 45%; Lower Half: 75%; Girdle: Medium, Faceted (3.5%); Culet: None

based on the specs it looks like a very nice stone. I wouldn't mine owing a stone with these specs...

 

[John P]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

How likely is this stone going to have painted girdles?

GIA has rather strict tolerances for painting and digging; so no worries on that count.

I'm no expert but from what I know so far, it seems you can't be safe unless you have an idealscope/ASET image and then post them here to get the expert opinions.

Much more can be meaningfully determined that way, as opposed to making educated-guesses based on grading report numbers.

 

[John P]

Re: Does 34.5 crown angle go well with 45% star and 75% LGF

Per Yssie: On its face 55-408-345-45-75 is not an issue. But it depends on how specific you want to get.

Impossible to say more because, aside from table, the data points are averages of 8-16 separate measurements apiece. Those averages are further rounded up-or-down if it's a GIA report. From this data there's no way to know how consistent the cutting is facet-by-facet, if that is important to you.

From the mouths of experts

Looking right back at you Yssie.

A side note; really nice advice and guidance in this thread.
https://www.pricescope.com/community/threads/why-is-this-diamond-rated-a-gia-very-good-cut.191875/