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Princess Diamonds Ideal Proportions?

Does anybody on list know what the “Ideal proportions” are for a
0.75ct Princess cut are? I have had a quick look in the archive but
have been unsuccessful. Or can anybody point me to a resource on
the net where I could obtain such

Thanking you in advance
Will Francis

It’s funny you should bring this up today, as just this afternoon my
manager was leafing through one of the trade magazines and she said
oh look they do have ideal radiant (or possibly princess) cut
diamonds. My contention to her was that you can only have "ideal"
cut round diamonds as that is the only shape on which a significant
amount of research has been done about what is “ideal”. However,
since even the GIA can no longer agree that there is an “ideal” cut
anymore (despite teaching it for more than 30 years), I would think
that some firm that sells radiant cuts has simply added it as a
marketing ploy. This, however, is an uninformed opinion, and it is
possible that someone has actually done research on it. If I can
find the advertisement again I will forward the name of the company
that was using it. Perhaps they could help with the actual

Daniel R. Spirer, GG
Spirer Somes Jewelers
1794 Massachusetts Ave
Cambridge, MA 02140

Will, There is no such thing as “Ideal” proportions for Princess
cuts The mu ch mis-used term “Ideal” can only be applied to rounds,
where there is at least SOME agreement on what angles and proportions
result in a minmum amount of light leakage There are at least a
couple of groups trying to work out some parameters for fancy cuts,
but there is certainly no agreement on what parameters are 20 "best"
for Princess cuts First, “best” would have to be defined, and, well,
good luck

Wayne Emery

Will, suggest you check out for all kinds of
on diamond cuts.

Cheers from Don at the Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1

Hello , The fancy shaped diamonds have the widest differences in
cutting standards and a great deal of dissension in specifics of
cutting proportions . The AGS [American Gem Society ], arguably along
with the GIA as the leading gem lab in such research , lab has moved
away from trying to “list” angles and proportions , they are in the
process of using a "performance " based crieria . They use a viewing
device , related to the Firescope {tm} to see how much light is
actually returned to the viewers eye . Firescopes are rare
instruments , if you ever have the chance to use one , it can be
mindblowing , how much light "leaks " out of diamonds , especially
fancy cuts . Typically the average princess cut can leak 50% of the
light it recieves . A really well cut round will return better than
99.5% of light . Probably the best attempt to quantify proportions in
fancy cut diamonds is the list developed by Dave Atlas , [ Accredited
Gem Appraisers , D. Atlas & Company ] they list NO SET OF
PROPORTIONS AS IDEAL for the princess cuts , however if you study the
charts you can get clues for better quality in princess cutting .
Also available from Dave’s site is the Holloway “ideal-scope” which
can help give you clues about performance in monds - see also and . This “ideal-scope” is
inexpensive and works , in my opinion and from direct comparison ,
about 80% as well as a Firescope . You MUST take measures to create
/ use standardized conditions during the use of the idealscope . In
My Opinion it can be a useful device . With all this as background
there are IDEAL CUT princess’s out there . I have found TWO in the
last three years that give 95% or better light return in the
firescope . What they have in common is , close to square shape
shape , relatively high total depth [to rounds] , A SIGNIFICANT
CROWN , and small [relative to other princess ] table . If you really
study , observationally , the differences between diamonds , you can
develop the eye to see greater reflectivity [ total light return ]
in diamonds . In the Princess the number one thing to look for is
dispersion , if the stone has a hard , dark even , look AND is
full of fire {rainbow effects} you are well on your way to buying a
well made one . More commonly you see excessive tables and a
superficial *brilliance * with little fire . A test you can use ,
with any shape diamond is to set it down on a " V " groove in a
piece of colored paper , the more light a diamond leaks , the more
color of the paper you will see in the body of the stone on the
paper . Hope this was useful…

Mark Clodius
Clodius&Co. Jewelers

Hello again , Sorry , since I posted the reply, I took a moment to
look up Dave Atlas’s site ,

and discovered since I had last recieved his list that he DOES , now
, list "ideal " proportions for the princess cut . The rest of the
comments still apply .

Mark Clodius