Radiant proportions for best optics

[mogedon]

Hi all,

I've narrowed my search down to a fancy coloured 2ct square radiant diamond and I'm looking to buy off the internet, but it's extremely tough to work out ideal optics for a radiant cut. The IGI certification doesn't give a cut grade and from what I've been reading looking at table(%) to depth(%) seems to only be useful for avoiding a truly awful cut:

[URL='https://www.pricescope.com/community/threads/radiant-cut-proportions.13219/']https://www.pricescope.com/community/threads/radiant-cut-proportions.13219/[/URL]

http://www.diamondreview.com/forum/topic/3620-radiant-diamond/

Does anyone know the best proportions for a cut corner square modified brilliant cut radiant of around 2cts? First priority is a diamond that throws off the best brilliance/scintillation, but I'm also looking to maximise the apparent size of the diamond and thus avoid buying useless cts.

I've come across Henry Grossbard's standards (http://www.washingtondiamond.com/Diamonds/The-Science-Behind-It). Would this be a good guide to follow?

Another thought that has occurred to me is to order the diamond and take it in for ASET imagery, if it's terrible value for money I can take advantage of the 60 day money back guarantee. Maybe my best bet?

Thanks

 

[MelisendeDiamonds]

The purpose for the cut of a Radiant is not usually the same as it is for a round brilliant and some of the other fancy shape designs.

So before I offer advice on "best optics" I'd like to ask you what attracted you to a Radiant cut over all other outline shapes. I'd be interested to know what characteristics are most important to you in a diamond and how you would rank some or all of the following in terms of importance.

1) an outline that has cut corners
2) an outline that has sharp edges
3) square outline or rectnagular outline
4) larger faceup size
5) brightness
6) fire (colored flashes)
7) fast scintillation (a sea of small tiny sparkles that flash on and off quickly when the diamond is moved)
8 ) big bold flashes
9) cheaper per carat

 

[Rockdiamond]

I agree with needing to find out what the OP wants to properly advise

I would ask more simple questions with regards to what mogedon love sto see in a diamond.
We already know op wants a radiant cut- so that means straight edges and cut corners.
mogedon- would you prefer a stone that has an organized pattern of light return?
Something like what H&A looks like in a round diamond Organized patters of larger flashes. On stones cut in this style, you will have contrast- the larger facets flash on and off.
versus
Stones with tiny, yet far more flashes in a distinct lack of patterning- not a lot of darker areas. There won't be a lot of contrast, but far more scintillation.

That's just considering an oversimplified explanation of the "light performance". You mentioned "brilliance, and scintillation" in the same breath. By certain definitions they are contrary phenomena to some extent. Not my definitions....

The Original Radiant Cut is like the second one.

 

[mogedon]

The purpose for the cut of a Radiant is not usually the same as it is for a round brilliant and some of the other fancy shape designs.

So before I offer advice on "best optics" I'd like to ask you what attracted you to a Radiant cut over all other outline shapes. I'd be interested to know what characteristics are most important to you in a diamond and how you would rank some or all of the following in terms of importance.

Thanks Melisende - After seeing the performance of the August Vintage cut from Good Old Gold I'd probably rank them in the following:

MOST IMPORTANT
4) larger faceup size
8 ) big bold flashes
6) fire (colored flashes)
5) brightness
3) square/rectangular outline - whichever maximises the above
LEAST IMPORTANT

I'd like to avoid the "crushed ice" look but I'm not wedded to a particular fancy cut (no pun intended ); a radiant or cushion would both suit. I'm sure I want to avoid the sharp edges too i.e. princess cut, and hoping for something a bit more unusual than the round brilliant.

As far as optical symmetry goes Rockdiamond, or an organised pattern of some kind, I'm not too fussed as long as there is still good light return. So I guess my question should be can I expect to be able to figure all these things out from a report or is it all just impossible without ASET or some equivalent report?

Thanks again!

 

[MelisendeDiamonds]

The purpose for the cut of a Radiant is not usually the same as it is for a round brilliant and some of the other fancy shape designs.

So before I offer advice on "best optics" I'd like to ask you what attracted you to a Radiant cut over all other outline shapes. I'd be interested to know what characteristics are most important to you in a diamond and how you would rank some or all of the following in terms of importance.

Thanks Melisende - After seeing the performance of the August Vintage cut from Good Old Gold I'd probably rank them in the following:

MOST IMPORTANT
4) larger faceup size
8 ) big bold flashes
6) fire (colored flashes)
5) brightness
3) square/rectangular outline - whichever maximises the above
LEAST IMPORTANT

I'd like to avoid the "crushed ice" look but I'm not wedded to a particular fancy cut (no pun intended ); a radiant or cushion would both suit. I'm sure I want to avoid the sharp edges too i.e. princess cut, and hoping for something a bit more unusual than the round brilliant.

As far as optical symmetry goes Rockdiamond, or an organised pattern of some kind, I'm not too fussed as long as there is still good light return. So I guess my question should be can I expect to be able to figure all these things out from a report or is it all just impossible without ASET or some equivalent report?

Thanks again!

Based on your preferences I think you will have trouble finding a Radiant that meets your criteria for big bold flashes and fire. Instead you should probably focus on modern (non H&A) or vintage faceted cushions.

Yes if you can't view the stones in person prior to purchase I think images like the ASET will be important for obtaining what you want. The limited and averaged numbers on a grading report are not going to be enough to select candidates which are optimized for brightness, fire, and big bold flashes.

I would suggest asking for help in your search from the consumer posters here as trademembers are not supposed to comment or promote other vendor's offerings.

 

[RADIANTMAN]

Mogedon - the generic radiants and cushions on the market include a wide variety of looks and there is no substitute for looking at diamonds yourself to decide which look you find most attractive. I noticed that you said you don't want the "crushed ice" look. Its important to realize that the phrase, which is often used to disparage radiants by those who don't like them, has a different meaning to different people. I have often shown what I consider beautiful radiants to folks who say they don't like the "crushed ice" look and had them respond "that's beautiful - that's not what I meant by crushed ice."

Once you decide what look you like (not one someone tells you is better), you can move to the next step which is finding the right one for you. The idea behind a "brand" is that the diamonds should be consistent in terms of providing a particular look. If the look you like matches up with a particular "brand" look, then buying the brand will be the safest way forward though it will likely involve a bit of a premium. You can also try to find a generic that matches the look but without actually seeing the diamond there is no way of knowing for sure if it does and most will not. You can gather data like ASET etc, but the data is only as good as your ability to interpret it and gleaning from data what a fancy shaped diamond will actually look like live is a very tricky endeavor.

 

[RADIANTMAN]

I just noticed you were looking for a fancy color diamond. Fancy color diamonds, when properly cut, are cut differently than colorless diamonds because the intensity and evenness of the color is a high priority. Large flashes are not considered desirable because diamonds cut to optimize those flashes do not optimize the color. Even those who don't like what they disparagingly call "crushed ice" generally acknowledge that fancy color diamonds are best cut in that style.

There is, in my opinion, no substitute in buying fancy color diamonds to seeing the diamond yourself, or if you can't, buying it from a trusted vendor with experience in fancy colors.

 

[Rockdiamond]

Great answers Radiantman!!
The term "crushed ice" is a real problem, along with the term "leakage"

mogedon- I too missed the fancy yellow aspect.
A huge majority of all Fancy Colored stones are cut with a lot of scintillation.
The main exception is step cut Yellows- which are very rare.
Even rarer are true chunky style cushions cut with yellow rough.
We have experimented along with Yoram F on such stones.
Like step cuts, they produce a different type of color, as most people percieve it.


As Stan mentioned, there's a huge variety of generic radiant cut facet models.
Some do have a number of larger reflections, others are tiny reflections, from edge to edge.
I could make a case that such stones ( those with no larger reflections) are "the best" - because they tend to have the most even color projection.
BUT, there's aspects to stones that do show more contrast that people find very attractive.
As Stan mentioned, there's just no substitute for looking at stones to see what you love.

We have used ASET to look at Yellow diamonds- personally I feel that one really needs to understand what they are looking at for ASET to have any value whatsoever. Posting an ASET for others to judge, if you don't know how to read it yourself will only tell you what other people like- your taste may vary
You already know how to judge a photograph- which is why I feel that photos and video are far more important to consumers.

 

[chrono]

Unfortunately, there is no specific combination or even generic guideline for buying a good performing fancy yellow radiant diamond. I don't think there is any cut grade assigned by any lab at the present time. In addition, I would not purchase from IGI because I am not confident that their colour grading is sufficiently stringent. For most, colour is what they go for in buying an FCD with a good balance of optics. There are often times trade-offs, such as a bit of added depth which adds to the depth of colour. It may well be almost impossible to find that perfect FCD you are looking for (combination of colour, cut, type of flash, etc). ASET will do little good because FCDs are cut very differently than white diamonds. Radiant FCDs are cut to trap colour, not to maximize light return the way a white coloured radiant is.

 

[MelisendeDiamonds]

Are you looking for a Fancy Yellow or do you want a yellow tinted body color (K-Z) to your diamond?
That was not written in your posts in THIS thread. If you want the yellow color this changes things considerably.

 

[Rockdiamond]

In my experience, the very best stones of the lower alphabet ( U-V, W-X, and Y-Z)- are cut exactly like a Fancy Light Yellow.
One thing mogedon mentioned is size for the weight.
That's a huge factor for me when I'm considering the purchase of a diamond.
The best cutters can work magic with stones in the low '60's depth- and give very good spread for the weight.