number of facets

If I would like my diamond to show the same briliance and less fire (cause
some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means less
briliance, therefore less fire?
b) A stone with more facets, since more facets means smaller facets,
therefore less visible fire?

And there's the dillema...less facets means bigger facets so yes, flashes of
fire will be less frequent, but once they show, they really show! On the
other hand, more facets means they are smaller in size, therefore less
capable of showing very noticable fire. I'm asking since I love the
briliance in diamonds, but don't like the dispersion that much. Any help?!
Thank you!

On Tue, 22 Mar 2005 17:58:50 -0800, in |õ "m4816k"
wrote:

If I would like my diamond to show the same briliance and less fire (cause
some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means less
briliance, therefore less fire?
b) A stone with more facets, since more facets means smaller facets,
therefore less visible fire?

And there's the dillema...less facets means bigger facets so yes, flashes of
fire will be less frequent, but once they show, they really show! On the
other hand, more facets means they are smaller in size, therefore less
capable of showing very noticable fire. I'm asking since I love the
briliance in diamonds, but don't like the dispersion that much. Any help?!
Thank you!


Actually, Marijan, you're looking at the wrong thing here. The number of facets is not
what changes the "fire" in a diamond. Lets review, for a moment, the different main
optical properties you see.

1. First, is brilliance. That is the reflectivity of the stone, or it's ability to
return as much total light as possible to the eye. A mirror, because it's able to
reflect all light hitting it, is very brilliant, a property taken advantage of with
inexpensive foil back rhinestones. By treating the pavilions of the stones with a
mirrored backing, foilbacks become very very brilliant and bright.

Diamonds owe their brilliance to several aspects of their cutting. The most important
is the angle of the pavilion facets, which determines whether light which enters the top
of the stone (all the light that matters in this discussion, is light that comes in the
top. light coming from the back or sides of a diamond generally also exit that way) If
the pavilion of the diamond is too shallow, light tends to go right through, making a
stone you can see things through, but which won't give you a lot of light return
(brilliance). A stone with too deep a pavilion will just look dark. So first, for
maximium brilliance, one needs the correct pavilion angle.

Second is simply the issue of how much light can enter the stone in order to be
reflected back. The table facet is the most effective window into the stone in which
light can enter and be reflected by the pavilion, back to the eye. So to a point, a
stone with a larger table may be more brilliant than one with a smaller table.

2. Second is fire, or as it's more correctly called in gemological terms, "dispersion".
This is the breaking up of light into the little flashes of colored light, even though
the light that entered the stone started out as just plain white light. It is the
result of light either entering or exiting the stone at an angle to a facet, when it can
be refracted into it's spectral colors. Because in general, when judging the fire or
dispersion of a stone, we're talking about the 'face up" view, light that enteres or
exits the stone, in order to do so at an angle, generally is not light that entered and
exited through the table facet, since we're looking at that straight on. So the facets
that play the most important part of fire, are the facets on the crown other than the
table. This holds true as well, even when one is looking at the stone at a bit of an
angle, since as you tip the stone, you're still less likely to then be seeing light that
entered and exited through the table, and once again, the crown facets are what matter.
Two things need to be there for good fire in a diamond. One is that the crown facets
have to be at a suitable angle. If the crown is very shallow, then the angle at which
light enters and exits a given facet is not much off of perpendicular, so little
refraction takes place. If the crown angle is too high, however, then it tends to
scatter light too much to the side, and not only does less light get into the stone, but
less of what does, is then visible to the viewer, as it gets more scattered to the
sides. The second is that there has to be a suffient surface area of crown facets in
the first place. If the table of the stone is very large (as may be the case with many
emerald cuts and princess cuts, especially), then even if the crown facets are at a good
angle for refraction, there is so little area of these facets to collect or disperse
light, that you simply don't see much fire. The best appearance will be with a stone
that has the correct crown angles, to best see the most fire, as well as a proper
pavilion angle so the fire is balanced with good brilliance, and with a stone that has a
good balance between the size of the table facet, and the area devoted to crown facets.
Lower crown angles and larger tables give less fire.

Often seen with older stones (prior to world war 2, and especially prior to world war 1)
are old european and old mine cut stones which may show a lot of fire, due to very high
crown angles and very small tables. But their often deep pavilions, and the too high
crowns and small tables, also mean little brilliance. These stones are most likely to
be those where one feels there may be too much fire.

Fire and brilliance are generally both considered essential to a good appearance in
diamond, but the two properties are not totally attainable at the same time. maximizing
the brilliance in a stone will reduce the fire, while maximizing the fire will reduce
the brilliance after a certain point. The exact balance of the two is a matter of
preference.

3. Finally, less often discussed and understood, is the property of "scintillation"
That may be best described as the sense of "movement" and livelyness as you move the
stone or your angle of view. facets sparkle and shimmer, light dances, the appearance
changes as the stone moves. Scintillation is dependent on the same qualities that give
a stone brilliance and fire. Plus more. Good polish, with good symmetry and precision
to the facetting improves scintillation, as does the number of facets. More facets give
a larger number of sparkles. As you note, the more there are, the smaller individual
ones are. So it's difficult to say just how many facets there must be, but most people
will prefer the standard 58 facet round brilliant with typical sizes. Very small stones
may benefit from having fewer facets, so the overall look remains sparkly, instead of
individual flashes becoming so small the stone just looks fuzzy. And larger stones may
be candidates for some of the newer variations on brilliant cutting which offer more
facets, or more complex patterns of facets.. Much of this is a matter of taste on the
part of the viewer, as much as it is a matter of the skill of the cutter.

What is considered a good amount of fire by one viewer may be too much or too little for
another, while most people prefer a stone with good scintillation and good brilliance.
Exactly how these properties are balanced to each other determines a good deal of the
cutting quality, but the exact proportions one should have are a matter of opinion, a
balance between the three properties. You cannot totally maximize all of them at the
same time, but one can come up with a set of proportions that seem to visually maximize
and balance all three to best effect. The commonly referred to "ideal cut" in diamond
is exactly such a balance. Determined mathematically and visually to be a set of
proportions which balances fire and brilliance best, it is still a subjective decision,
and there are more than one definitions of exactly what is ideal. People who prefer a
look with less fire may wish a stone with a larger table, and perhaps even a shallower
crown angle. Doing this will lessen fire, but may increase brilliance to a degree.
Overdoing it will reduce scintillation, which may make the stone less lively looking.
The added factor is that with the economics of cutting, a stone cut for more brilliance
and less fire, with a larger table and shallower crown angles, may cost less because
less of the rough crystal must be ground away.. That translates to a choice between a
stone with maximized brilliance and fire (ideal cut), or one with less fire and perhaps
less scintillation, but good brilliance, and importantly, perhaps a larger visual size
(diameter and weight both) for the same amount of money.

With all that said, you'll see that the bottom line in your quest to get a different
amount of fire in your stone generally is the balance between table size and crown
angles, not the size of the facets. You should also, if you prefer a stone with less
fire, stay away from emerald cuts. The parallel long facets on these can make
especially good prisms, giving larger than usual flashes of a single spectral color,
when the stone is well cut. And at least one of the common modern cuts, the princess
cut, due to it's often larger table, usually has less fire than many other cuts. But
it's complex pavilion facet pattern seems to often make up for the usual loss in
scintillation, so these stones are often very brilliant and lively, despite the large
table size.

Hope that helps.

Peter Rowe

Select a WELL CUT colorless sapphire, chrysoberyl or spinel instead of
diamond. Or perhaps a black or very dark brown diamond. Much of the
spectra would be absorbed. The dipersion is a physical property that
would be difficult to control to a significant degree. Plus, you will
have an uncommon stone instead of 'just another diamond'.

Carl
1 Lucky Texan


m4816k wrote:

If I would like my diamond to show the same briliance and less fire (cause
some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means less
briliance, therefore less fire?
b) A stone with more facets, since more facets means smaller facets,
therefore less visible fire?

And there's the dillema...less facets means bigger facets so yes, flashes of
fire will be less frequent, but once they show, they really show! On the
other hand, more facets means they are smaller in size, therefore less
capable of showing very noticable fire. I'm asking since I love the
briliance in diamonds, but don't like the dispersion that much. Any help?!
Thank you!



--
to reply, change ( .not) to ( .net)

Terrific notes, Peter!
It slightly obliquely leads to a question about the relationship of t=
he=20
correct angle of the pavilion to the refractive index of the material=
..=20
There should be a simple relationship.

You were discussing diamonds, but the same principles apply to other=
=20
gems. I have been wondering whether the companies who cut CZ "diamon=
ds"=20
use the same angles as those used for diamonds or whether they use th=
e=20
correct one for the CZ refractive index.

Thank you,
David.

Peter W.. Rowe, wrote:

On Tue, 22 Mar 2005 17:58:50 -0800, in |=07=F5 "m4816k"
wrote:
=20
=20
If I would like my diamond to show the same briliance and less fir=
e (cause
some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means=
less
briliance, therefore less fire?
b) A stone with more facets, since more facets means smaller facet=
s,
therefore less visible fire?

And there's the dillema...less facets means bigger facets so yes, =
flashes of
fire will be less frequent, but once they show, they really show! =
On the
other hand, more facets means they are smaller in size, therefore =
less
capable of showing very noticable fire. I'm asking since I love th=
e
briliance in diamonds, but don't like the dispersion that much. An=
y help?!
Thank you!

=20
=20
Actually, Marijan, you're looking at the wrong thing here. The nu=
mber of facets is not
what changes the "fire" in a diamond. Lets review, for a moment, t=
he different main
optical properties you see.
=20
1. First, is brilliance. That is the reflectivity of the stone, o=
r it's ability to
return as much total light as possible to the eye. A mirror, becau=
se it's able to
reflect all light hitting it, is very brilliant, a property taken a=
dvantage of with
inexpensive foil back rhinestones. By treating the pavilions of th=
e stones with a
mirrored backing, foilbacks become very very brilliant and bright.
=20
Diamonds owe their brilliance to several aspects of their cutting. =
The most important
is the angle of the pavilion facets, which determines whether light=
which enters the top
of the stone (all the light that matters in this discussion, is lig=
ht that comes in the
top. light coming from the back or sides of a diamond generally al=
so exit that way) If
the pavilion of the diamond is too shallow, light tends to go right=
through, making a
stone you can see things through, but which won't give you a lot of=
light return
(brilliance). A stone with too deep a pavilion will just look dark=
.. So first, for
maximium brilliance, one needs the correct pavilion angle.
=20
Second is simply the issue of how much light can enter the stone in=
order to be
reflected back. The table facet is the most effective window into =
the stone in which
light can enter and be reflected by the pavilion, back to the eye. =
So to a point, a
stone with a larger table may be more brilliant than one with a sma=
ller table.
=20
2. Second is fire, or as it's more correctly called in gemological=
terms, "dispersion".
This is the breaking up of light into the little flashes of colored=
light, even though
the light that entered the stone started out as just plain white li=
ght. It is the
result of light either entering or exiting the stone at an angle to=
a facet, when it can
be refracted into it's spectral colors. Because in general, when j=
udging the fire or
dispersion of a stone, we're talking about the 'face up" view, ligh=
t that enteres or
exits the stone, in order to do so at an angle, generally is not li=
ght that entered and
exited through the table facet, since we're looking at that straigh=
t on. So the facets
that play the most important part of fire, are the facets on the cr=
own other than the
table. This holds true as well, even when one is looking at the st=
one at a bit of an
angle, since as you tip the stone, you're still less likely to then=
be seeing light that
entered and exited through the table, and once again, the crown fac=
ets are what matter.
Two things need to be there for good fire in a diamond. One is tha=
t the crown facets
have to be at a suitable angle. If the crown is very shallow, then=
the angle at which
light enters and exits a given facet is not much off of perpendicul=
ar, so little
refraction takes place. If the crown angle is too high, however, t=
hen it tends to
scatter light too much to the side, and not only does less light ge=
t into the stone, but
less of what does, is then visible to the viewer, as it gets more s=
cattered to the
sides. The second is that there has to be a suffient surface area =
of crown facets in
the first place. If the table of the stone is very large (as may b=
e the case with many
emerald cuts and princess cuts, especially), then even if the crown=
facets are at a good
angle for refraction, there is so little area of these facets to co=
llect or disperse
light, that you simply don't see much fire. The best appearance wi=
ll be with a stone
that has the correct crown angles, to best see the most fire, as we=
ll as a proper
pavilion angle so the fire is balanced with good brilliance, and wi=
th a stone that has a
good balance between the size of the table facet, and the area devo=
ted to crown facets.
Lower crown angles and larger tables give less fire.
=20
Often seen with older stones (prior to world war 2, and especially =
prior to world war 1)
are old european and old mine cut stones which may show a lot of fi=
re, due to very high
crown angles and very small tables. But their often deep pavilions=
, and the too high
crowns and small tables, also mean little brilliance. These stones=
are most likely to
be those where one feels there may be too much fire.
=20
Fire and brilliance are generally both considered essential to a go=
od appearance in
diamond, but the two properties are not totally attainable at the s=
ame time. maximizing
the brilliance in a stone will reduce the fire, while maximizing th=
e fire will reduce
the brilliance after a certain point. The exact balance of the two=
is a matter of
preference. =20
=20
3. Finally, less often discussed and understood, is the property o=
f "scintillation"
That may be best described as the sense of "movement" and livelynes=
s as you move the
stone or your angle of view. facets sparkle and shimmer, light dan=
ces, the appearance
changes as the stone moves. Scintillation is dependent on the sam=
e qualities that give
a stone brilliance and fire. Plus more. Good polish, with good sy=
mmetry and precision
to the facetting improves scintillation, as does the number of face=
ts. More facets give
a larger number of sparkles. As you note, the more there are, the =
smaller individual
ones are. So it's difficult to say just how many facets there must=
be, but most people
will prefer the standard 58 facet round brilliant with typical size=
s. Very small stones
may benefit from having fewer facets, so the overall look remains s=
parkly, instead of
individual flashes becoming so small the stone just looks fuzzy. A=
nd larger stones may
be candidates for some of the newer variations on brilliant cutting=
which offer more
facets, or more complex patterns of facets.. Much of this is a mat=
ter of taste on the
part of the viewer, as much as it is a matter of the skill of the c=
utter.
=20
What is considered a good amount of fire by one viewer may be too m=
uch or too little for
another, while most people prefer a stone with good scintillation a=
nd good brilliance.
Exactly how these properties are balanced to each other determines =
a good deal of the
cutting quality, but the exact proportions one should have are a ma=
tter of opinion, a
balance between the three properties. You cannot totally maximize =
all of them at the
same time, but one can come up with a set of proportions that seem =
to visually maximize
and balance all three to best effect. The commonly referred to "i=
deal cut" in diamond
is exactly such a balance. Determined mathematically and visually =
to be a set of
proportions which balances fire and brilliance best, it is still a =
subjective decision,
and there are more than one definitions of exactly what is ideal. =
People who prefer a
look with less fire may wish a stone with a larger table, and perha=
ps even a shallower
crown angle. Doing this will lessen fire, but may increase brillia=
nce to a degree.
Overdoing it will reduce scintillation, which may make the stone le=
ss lively looking.
The added factor is that with the economics of cutting, a stone cut=
for more brilliance
and less fire, with a larger table and shallower crown angles, may =
cost less because
less of the rough crystal must be ground away.. That translates to=
a choice between a
stone with maximized brilliance and fire (ideal cut), or one with l=
ess fire and perhaps
less scintillation, but good brilliance, and importantly, perhaps =
a larger visual size
(diameter and weight both) for the same amount of money.
=20
With all that said, you'll see that the bottom line in your quest t=
o get a different
amount of fire in your stone generally is the balance between table=
size and crown
angles, not the size of the facets. You should also, if you prefer=
a stone with less
fire, stay away from emerald cuts. The parallel long facets on the=
se can make
especially good prisms, giving larger than usual flashes of a singl=
e spectral color,
when the stone is well cut. And at least one of the common modern=
cuts, the princess
cut, due to it's often larger table, usually has less fire than man=
y other cuts. But
it's complex pavilion facet pattern seems to often make up for the =
usual loss in
scintillation, so these stones are often very brilliant and lively,=
despite the large
table size.
=20
Hope that helps.
=20
Peter Rowe

m4816k wrote:
If I would like my diamond to show the same briliance and less fire (cause
some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means less
briliance, therefore less fire?


Only two possible choices, either a Context Cut diamond or a Spirit Sun cut
diamond. Both designed by Bernd Munsteiner. Very few places in the US can get
these stones. I am one of the lucky few. If you are interested, please contact
me directly. A warning. They are expensive. Very expensive.

Both of these cuts have fewer facets that a brilliant cut diamond. The Context
Cut has only 8, the Spirit Sun has 32, and both show MORE brilliance than a
brilliant cut diamond. This was measured by the renowned Fraunhofer Institut in
Jena.

The brilliance of a brilliant cut diamond was set at 100, the Context Cut
measured 115.4, and the Spirit Sun 117.3

BTW, I hope you realize, that with a question like the one you asked, you have
set yourself up for a voluminous reply from Peter. I bet he won't be able to
keep this under 6 paragraphs. Long paragraphs.

Abrasha
http://www.abrasha.com

On Tue, 22 Mar 2005 21:56:55 -0800, in hõ DPS wrote:


Terrific notes, Peter!
It slightly obliquely leads to a question about the relationship of the
correct angle of the pavilion to the refractive index of the material.
There should be a simple relationship.

Each gem material has it's ideal pavilion angle. Any decent book on gem cutting will
show you the recommended angles for crown and pavilion. However, some of it depends on
the cut itself, and many of the cuts used in colored stones, will alter these angles to
achieve different effects. In other cases, the optics of the cut itself will require
different angles. Classics include the princess cuts, where the optical activity
(reflections from one pavilion side to the other) occur along the diagonal direction of
the stone. In that profile, the angles are typical, but the usual way of measureing and
describing them in diamond cutting would make them seem way too deep. Other cases are
things like marquise cuts, where pavilion facets extend to a culet from widely varying
distances from the center of the stone, so the pavilion angles vary as one moves from
the side to the ends. The cutter must find an attractive average, and this can vary
quite a bit from stone to stone.


You were discussing diamonds, but the same principles apply to other
gems. I have been wondering whether the companies who cut CZ "diamonds"
use the same angles as those used for diamonds or whether they use the
correct one for the CZ refractive index.

From what I've seen, I THINK the best cut CZs use the correct angle for CZ, not those
for diamonds. I will say, though, that I don't recall ever specifically measuring them
to find out. They seem to, however, since most C.Z.s have a slightly different look,
most notably with a slight change in the appearance of the reflection of the table in
the stone (a usually darkish shadow in the center. With most CZs, that reflection
appears slightly larger, and slightly darker than in well cut diamonds, because of a
slightly deeper angle used in CZs, much the same as with a diamond that cut slightly too
deep. I've always assumed that if they used a shallower pavilion angle to match the
table reflection size, that it would then start to window too much. But as I said, i've
not actually checked that.

Peter

When I cut CZ or any material, I begin with appropriate angles to
prevent windowing,(curiously, 42deg pavilion angles work well for a LOT
of materials!) then, after the cut is designed or selected, I translate
the angles to try to maximize brilliance. With synthetics there is
usually no issue with depth. Plus. CZ's RI is higher than diamond's so
there may be no reason, in most cases, to use deeper pavilion angles and
there may be good reasons to use shallower angles. Much can depend on
the outline of the cut selected, 'pointy' cuts are notoriously dark in
the points - moreso in lower RI materials, and sometimes very high
angles (50deg or so) IN THAT AREA ALONE, can help pump a little more
brilliance out. Faceting is a fun and interesting hobby for me, if you
want to do more reading....

check;
http://www.gemcad.com/
http://www.gemsociety.org/
http://www.yourgemologist.com/


Carl
1 Lucky Texan


DPS wrote:
Terrific notes, Peter!
It slightly obliquely leads to a question about the relationship of t=
he=20
correct angle of the pavilion to the refractive index of the material=
.=20
There should be a simple relationship.

You were discussing diamonds, but the same principles apply to other=
=20
gems. I have been wondering whether the companies who cut CZ "diamon=
ds"=20
use the same angles as those used for diamonds or whether they use th=
e=20
correct one for the CZ refractive index.

Thank you,
David.

Peter W.. Rowe, wrote:


On Tue, 22 Mar 2005 17:58:50 -0800, in |=07=F5 "m4816k"
wrote:
=20
=20

If I would like my diamond to show the same briliance and less fir=

e (cause

some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means=

less

briliance, therefore less fire?
b) A stone with more facets, since more facets means smaller facet=

s,

therefore less visible fire?

And there's the dillema...less facets means bigger facets so yes, =

flashes of

fire will be less frequent, but once they show, they really show! =

On the

other hand, more facets means they are smaller in size, therefore =

less

capable of showing very noticable fire. I'm asking since I love th=

e

briliance in diamonds, but don't like the dispersion that much. An=

y help?!

Thank you!


=20
=20
Actually, Marijan, you're looking at the wrong thing here. The nu=

mber of facets is not

what changes the "fire" in a diamond. Lets review, for a moment, t=

he different main

optical properties you see.
=20
1. First, is brilliance. That is the reflectivity of the stone, o=

r it's ability to

return as much total light as possible to the eye. A mirror, becau=

se it's able to

reflect all light hitting it, is very brilliant, a property taken a=

dvantage of with

inexpensive foil back rhinestones. By treating the pavilions of th=

e stones with a

mirrored backing, foilbacks become very very brilliant and bright.
=20
Diamonds owe their brilliance to several aspects of their cutting. =

The most important

is the angle of the pavilion facets, which determines whether light=

which enters the top

of the stone (all the light that matters in this discussion, is lig=

ht that comes in the

top. light coming from the back or sides of a diamond generally al=

so exit that way) If

the pavilion of the diamond is too shallow, light tends to go right=

through, making a

stone you can see things through, but which won't give you a lot of=

light return

(brilliance). A stone with too deep a pavilion will just look dark=

. So first, for

maximium brilliance, one needs the correct pavilion angle.
=20
Second is simply the issue of how much light can enter the stone in=

order to be

reflected back. The table facet is the most effective window into =

the stone in which

light can enter and be reflected by the pavilion, back to the eye. =

So to a point, a

stone with a larger table may be more brilliant than one with a sma=

ller table.

=20
2. Second is fire, or as it's more correctly called in gemological=

terms, "dispersion".

This is the breaking up of light into the little flashes of colored=

light, even though

the light that entered the stone started out as just plain white li=

ght. It is the

result of light either entering or exiting the stone at an angle to=

a facet, when it can

be refracted into it's spectral colors. Because in general, when j=

udging the fire or

dispersion of a stone, we're talking about the 'face up" view, ligh=

t that enteres or

exits the stone, in order to do so at an angle, generally is not li=

ght that entered and

exited through the table facet, since we're looking at that straigh=

t on. So the facets

that play the most important part of fire, are the facets on the cr=

own other than the

table. This holds true as well, even when one is looking at the st=

one at a bit of an

angle, since as you tip the stone, you're still less likely to then=

be seeing light that

entered and exited through the table, and once again, the crown fac=

ets are what matter.

Two things need to be there for good fire in a diamond. One is tha=

t the crown facets

have to be at a suitable angle. If the crown is very shallow, then=

the angle at which

light enters and exits a given facet is not much off of perpendicul=

ar, so little

refraction takes place. If the crown angle is too high, however, t=

hen it tends to

scatter light too much to the side, and not only does less light ge=

t into the stone, but

less of what does, is then visible to the viewer, as it gets more s=

cattered to the

sides. The second is that there has to be a suffient surface area =

of crown facets in

the first place. If the table of the stone is very large (as may b=

e the case with many

emerald cuts and princess cuts, especially), then even if the crown=

facets are at a good

angle for refraction, there is so little area of these facets to co=

llect or disperse

light, that you simply don't see much fire. The best appearance wi=

ll be with a stone

that has the correct crown angles, to best see the most fire, as we=

ll as a proper

pavilion angle so the fire is balanced with good brilliance, and wi=

th a stone that has a

good balance between the size of the table facet, and the area devo=

ted to crown facets.

Lower crown angles and larger tables give less fire.
=20
Often seen with older stones (prior to world war 2, and especially =

prior to world war 1)

are old european and old mine cut stones which may show a lot of fi=

re, due to very high

crown angles and very small tables. But their often deep pavilions=

, and the too high

crowns and small tables, also mean little brilliance. These stones=

are most likely to

be those where one feels there may be too much fire.
=20
Fire and brilliance are generally both considered essential to a go=

od appearance in

diamond, but the two properties are not totally attainable at the s=

ame time. maximizing

the brilliance in a stone will reduce the fire, while maximizing th=

e fire will reduce

the brilliance after a certain point. The exact balance of the two=

is a matter of

preference. =20
=20
3. Finally, less often discussed and understood, is the property o=

f "scintillation"

That may be best described as the sense of "movement" and livelynes=

s as you move the

stone or your angle of view. facets sparkle and shimmer, light dan=

ces, the appearance

changes as the stone moves. Scintillation is dependent on the sam=

e qualities that give

a stone brilliance and fire. Plus more. Good polish, with good sy=

mmetry and precision

to the facetting improves scintillation, as does the number of face=

ts. More facets give

a larger number of sparkles. As you note, the more there are, the =

smaller individual

ones are. So it's difficult to say just how many facets there must=

be, but most people

will prefer the standard 58 facet round brilliant with typical size=

s. Very small stones

may benefit from having fewer facets, so the overall look remains s=

parkly, instead of

individual flashes becoming so small the stone just looks fuzzy. A=

nd larger stones may

be candidates for some of the newer variations on brilliant cutting=

which offer more

facets, or more complex patterns of facets.. Much of this is a mat=

ter of taste on the

part of the viewer, as much as it is a matter of the skill of the c=

utter.

=20
What is considered a good amount of fire by one viewer may be too m=

uch or too little for

another, while most people prefer a stone with good scintillation a=

nd good brilliance.

Exactly how these properties are balanced to each other determines =

a good deal of the

cutting quality, but the exact proportions one should have are a ma=

tter of opinion, a

balance between the three properties. You cannot totally maximize =

all of them at the

same time, but one can come up with a set of proportions that seem =

to visually maximize

and balance all three to best effect. The commonly referred to "i=

deal cut" in diamond

is exactly such a balance. Determined mathematically and visually =

to be a set of

proportions which balances fire and brilliance best, it is still a =

subjective decision,

and there are more than one definitions of exactly what is ideal. =

People who prefer a

look with less fire may wish a stone with a larger table, and perha=

ps even a shallower

crown angle. Doing this will lessen fire, but may increase brillia=

nce to a degree.

Overdoing it will reduce scintillation, which may make the stone le=

ss lively looking.

The added factor is that with the economics of cutting, a stone cut=

for more brilliance

and less fire, with a larger table and shallower crown angles, may =

cost less because

less of the rough crystal must be ground away.. That translates to=

a choice between a

stone with maximized brilliance and fire (ideal cut), or one with l=

ess fire and perhaps

less scintillation, but good brilliance, and importantly, perhaps =

a larger visual size

(diameter and weight both) for the same amount of money.
=20
With all that said, you'll see that the bottom line in your quest t=

o get a different

amount of fire in your stone generally is the balance between table=

size and crown

angles, not the size of the facets. You should also, if you prefer=

a stone with less

fire, stay away from emerald cuts. The parallel long facets on the=

se can make

especially good prisms, giving larger than usual flashes of a singl=

e spectral color,

when the stone is well cut. And at least one of the common modern=

cuts, the princess

cut, due to it's often larger table, usually has less fire than man=

y other cuts. But

it's complex pavilion facet pattern seems to often make up for the =

usual loss in

scintillation, so these stones are often very brilliant and lively,=

despite the large

table size.
=20
Hope that helps.
=20
Peter Rowe



--
to reply, change ( .not) to ( .net)

" Fire" is determined more by facet angle, both pavilion and crown. The
number doesn't have much to do with it.
Look at 2 same sized stones side by side and you will notice one will have
more fire than the other even with the same design.
Gordon
"m4816k" wrote in message
...
If I would like my diamond to show the same briliance and less fire (cause
some tend to be a bit "too colorful"), I should choose:

a) A stone that has less facets, since less facets generally means less
briliance, therefore less fire?
b) A stone with more facets, since more facets means smaller facets,
therefore less visible fire?

And there's the dillema...less facets means bigger facets so yes, flashes
of
fire will be less frequent, but once they show, they really show! On the
other hand, more facets means they are smaller in size, therefore less
capable of showing very noticable fire. I'm asking since I love the
briliance in diamonds, but don't like the dispersion that much. Any help?!
Thank you!