princess cut

[palomino]

the princess cut seems to have very little sparkle..is this true, or my imagination?

 

[Richard Sherwood]

First, let's define the terms for "sparkle":

BRILLIANCE (return of light after being bounced around in the diamond)

SCINTILLATION (return of light which bounces off the outer surface)

DISPERSION (rainbow colors created by the spreading of the white light ray into it's R.O.Y.G.B.I.V. components)

The princess cuts seem to often have good brilliance, but lacking a little in the scintillation department and even more in the dispersion department.

This is usually because of the thinner crowns and wider tables which seem to be common among the princess cuts. Because the crown is thinner, there is less of the "prism length" on the angled facets between the table and girdle. This makes for less "rainbow" flashes.

Then, with a wide table, the surface area of the bezel facets (between the table and girdle) is smaller. This makes for one big "flash" of the table, and correspondingly smaller "flashes" of light from the bezel area facets (scintillation).

This diminishment of dispersion and scintillation is probably what you're noticing, possibly along with a "darkness" which occurs in the center of the princess cut when the pavilion is too deep.

Rich, GG
Sarasota Gemological Laboratory

 

[barry]

It's true, not just your imagination.

Until very recently, Princess Cuts have been
the refuge for diamond rough that is not amenable
to good yields for other shapes.
Manufacturers seeking to salvage money have cut Princess'
for maximum yield; the result is spready tables,
mimimum crowns and deep (bottom heavy) pavilions
that have poor brilliance, fire, and
scintillation.

With DeBeers concerted Ad campaign on behalf of Princess
Cuts, this shape has gained tremendous popularity
and some manufacturers are now cutting a superior stone,
sacrificing weight for superior light output.
Seek and you will find these beauties. They're
out there.

Barry
www.superbcert.com

 

[palomino]

----------------
On 11/2/2002 7:05:03 PM

First, let's define the terms for "sparkle":

BRILLIANCE (return of light after being bounced around in the diamond)

SCINTILLATION (return of light which bounces off the outer surface)

DISPERSION (rainbow colors created by the spreading of the white light ray into it's R.O.Y.G.B.I.V. components)

The princess cuts seem to often have good brilliance, but lacking a little in the scintillation department and even more in the dispersion department.

This is usually because of the thinner crowns and wider tables which seem to be common among the princess cuts. Because the crown is thinner, there is less of the "prism length" on the angled facets between the table and girdle. This makes for less "rainbow" flashes.

Then, with a wide table, the surface area of the bezel facets (between the table and girdle) is smaller. This makes for one big "flash" of the table, and correspondingly smaller "flashes" of light from the bezel area facets (scintillation).

This diminishment of dispersion and scintillation is probably what you're noticing, possibly along with a "darkness" which occurs in the center of the princess cut when the pavilion is too deep.

Rich, GG
Sarasota Gemological Laboratory
----------------



Thank you so much for the helpful info..I really appreciate it. Syd

 

[palomino]

----------------
On 11/2/2002 7:48:39 PM

It's true, not just your imagination.

Until very recently, Princess Cuts have been
the refuge for diamond rough that is not amenable
to good yields for other shapes.
Manufacturers seeking to salvage money have cut Princess'
for maximum yield; the result is spready tables,
mimimum crowns and deep (bottom heavy) pavilions
that have poor brilliance, fire, and
scintillation.

With DeBeers concerted Ad campaign on behalf of Princess
Cuts, this shape has gained tremendous popularity
and some manufacturers are now cutting a superior stone,
sacrificing weight for superior light output.
Seek and you will find these beauties. They're
out there.

Barry
www.superbcert.com
----------------

Thank you, this is very helpful. Syd