Fiery Princess?

[FB.]

What generalised set of proportions are likely to lean towards a princess-cut-equivalent of the fiery ideal cut in rounds?
In my eyes, far too many princess stones lack fire, yet can have very good light return and scintillation. Is that a result of the very small crowns often seen on princess cuts, or is a lack of fire an intrinsic part of a princess?

I''m guessing that some useful ingredients fore increasing fire in a princess would include a small-ish table, steeper crown angle and slightly shallower pavilion depth/angle (to compensate for the steeper crown).
But does anyone have some proportion guidelines - or even "gut instinct"?

Thanks
FB

 

[Paul-Antwerp]

The propensity to show or observe fire is related to both the light-environment and the build-up of the stone. As such, I do not really like the concept of the fiery-ideal-cut in rounds, since it is based on the build-up of the stone only.

In princess-cuts, the same is true. If one looks at build-up only, the fact that many princess-cuts have almost no crown really hurts their fire-potential.

But I do not agree that most princess-cuts are very good in brightness and scintillation. I find the majority of princess-cuts also under-performing in both these areas. And many well-cut princess-cuts have according to me crown angles that are too steep. Theoretically, that should help fire, I actually think that it hurts the fire-potential, since the listed crown angle is for the first step in the crown only, and the second non-reported crown angle is then way too shallow.

Finally, most princess-cuts have too many facets, thus reducing the size of the virtual facets. This reduces the chance for the observer to actually see fire.

Live long,

 

[FB.]

Thanks, Paul.

OK, so crown angle can be misleading, due to the double-angle. I guess the same is true of the bulged pavilion, in many cases.
Incidentally, from what I've seen, it seems as if many of the better-cut princess stones have less tendency for a double crown angle.

But what about crown height, when coupled with table width, to consider the average angle?

For example, a table width of 71% and a crown height of 12% would give an average crown angle around 40 degrees.

Can we make some generalisations for an average crown angle and an average pavilion depth that would have a higher-than-average chance of increasing the fire?

 

[tap02150]

I just wanted to say that i went with a whiteflash ACA princess and the diamond is absolutely perfect for me. It had a table of 68.6% and the crown angle was 44.6 degrees/13.5%. That being said, there are many other vendors that produce similar princess cut diamonds that are as superior. I would trust Whiteflash ACAs, Good Old Good''s Signature, as well as Infinity diamonds.

As paul said, the chevrons (number of total facets) has a huge perspective of fire. My princess cut has 3 chevrons.. cant remember what that means for # of facets.. but the flashes returned from light are a bit smaller than the 2 chevron diamonds that I looked at. There are also more flashes.

This link is a video of the difference of two princess cut diamonds, one has 2 chevrons, the other has 3. This will give you a better idea of what we are talking about. In addition, in this video, both diamonds are scoring VERY high on the light spectrum, including some of the most fire a princess cut can produce!

http://www.goodoldgold.com/videos/AGSPr2chev3chev.wmv

 

[Paul-Antwerp]

Date: 9/16/2009 8:45:46 AM
Author: FB.
Thanks, Paul.

OK, so crown angle can be misleading, due to the double-angle. I guess the same is true of the bulged pavilion, in many cases.
Incidentally, from what I''ve seen, it seems as if many of the better-cut princess stones have less tendency for a double crown angle.

But what about crown height, when coupled with table width, to consider the average angle?

For example, a table width of 71% and a crown height of 12% would give an average crown angle around 40 degrees.

Can we make some generalisations for an average crown angle and an average pavilion depth that would have a higher-than-average chance of increasing the fire?

Unfortunately, light does not react to average angles, but only to real angles. In that way, the average of two highly different angles will not work.

What I find the best combination has a lot of similarities with what works in rounds.

For the second pavilion mains (running from corner to culet), I prefer an angle around 42°. This is highly similar to the angle of the lower girdle halves in rounds.
In the main crown angle, I prefer an angle around 34° (again similar to rounds) and a table around 60%.

This generally results in a total depth of slightly above 75%.

Live long,

 

[strmrdr]

There are to many facets and angles that must all work together to judge any princess cut by the numbers.
To get a more fiery princess would be 2 chevron, smallish table and proper angles and the facets in the right places combined with superior optical symmetry to get the best out of them.
The numbers do not tell you enough of that information.

Lets look at the facet structure of a 2 chevron princess.
Each of the facet the arrows point to is repeated 4 times.
Each facet set not only has an angle but it also has a width and location.
I have seen a large variation in the width and location of the chevrons and pavilion facets.
Both width and location affect performance along with the angle.

With a RB the location and width of the facets can be defined with a few simple numbers not so with pricess cuts and other fancies.

 

[strmrdr]

If you are defining a princess by one pavilion angle and depth this one has the same numbers as the one I posted above.
See the extreme difference in structure?