What % for Cushion cut?

[naomi]

What kind of specs (table%, depth%) I should look for to find a very good cut cushion?

I thought I saw something like "use AGA class chart for round under x carat, use pear/marquise/heart guide for over xcarat....."
Can somebody give me some guidance?

 

[reena]

i was told to use a combo of the GIA cut charts for oval and radiant, and in fact that's what i did in selecting my stone.




i'm no expert, but when i tried to narrow cushion cut stones down by the numbers alone (just to get rid of the extremes) i eliminated anything with a table under 54 and over 66 and with a depth under 57 or over 75. (keep in mind this was just my own semi-arbitrary exercise--this doesn't mean you won't find a good cushion outside of those parameters.) then you can look at some stones in person and hone your preferences down further. for example, i tried to say away from stones in the 70s for depth simply because i found that you really start losing spread when you get up that high. i also tried to stay away from extremely thick girdles (same reason) or very thin girdles (chipping) and looked for at least VG symmetry and polish. (that's actually pretty tough to find in a cushion, you'll discover.) the other thing i did was to determine what range in length to width ratio i was willing to accept (go to www.gemappraisers.com and use the fancy shape selector for ovals), which narrowed it down even further.




so that system worked pretty well for me, but then step 2 was actually going to see the stones that met those specifications in person to make sure i liked the way they were cut. most of the time: i didn't! that's the hardest part. good luck.

 

[naomi]

To use Fancy shape selector, I have to register as an affiliate. Can individual consumer can register?

 

[reena]

oh--no, you don't actually have to register. sometimes it is very slow in loading. wait a minute and if it doesn't work try again in a few hours.

 

[moremoremore]

Dave (Oldminer) recently indicated that if the cushion is more square, that you can use the round guide and that if it is more rectangular, to use the oval. The key here is to get a good crown height. Dave also mentioned that a lot of cushions are usually cut way too deep (or way too shallow) and have very steep crowns. I guess the same holds true for a cushion: you need the right combo of crown and pavillion angles. I know a thick girlde makes you lose a little spread (but how much dunno)...but I would be less willing to take X thin than X thick for the same reasons as other shapes. Finding a good cushion online is a challenge but possible. First, I would decide if you like the old fashioned/old mine look or a newer, more modern brilliant look. I believe that you can kinda get a feel if you're dealing with an old cut by looking at the plot on the cert. Good luck in your search!!! p.s.: Even in a princess stone, I believe that a 1:06-1:07 ratio still looks very square...so think abou that too...but as reena suggest, the fancy shape selector is the best!!!

 

[moremoremore]

An example of a modern brilliant (as I call it) can be seen in this example I believe....Notice the facet pattern like the 8 rays of a round.

http://www.bluenile.com/diamonds_details.asp?pid=LD00327183&item=77_356&filter_id=0&sec=&query=&page=4&sortby=ranking

 

[cushioncut]

The table depth numbers I look for are depth between 58 and 65, and table ideally 3 points below the depth, typically around 55 to 65. I've found stones with smaller tables more appealing, but I think it's a matter of preference.

MMM -- you said crown height is important for cushions, in your opinion, what is an deal crown height? (Still stuggling about the low crown on the stone I have here. It's a 60.9% depth, and 9% crown, do you think it's too low?)

I also had the same plot theory, but I thought I made it up. I had noticed that the plots with four "stars" made for older looking stones. But then I started seeing exceptions to this. I've seen some stones with the four star pattern that look very brilliant and modern, and some, (like the one I have here) that have eight stars but have larger, older looking facets... I started to think the plots were random.

Experts, is it possible to determine the look of the stone from what the plot looks like? It would be very helpful if you could.

Good luck finding a cushion naomi!

 

[moremoremore]

Cushioncut....I'm BY NO MEANS ANY sort of expert on cushions...or anything for that matter

but here are some guesses

I think with all shapes, the key is to get the right crown and pavillion angles (not that I know what those are...that's a matter of the expert vendors on p.s. who know what to look for)... I wouldn't say that your stone's is horribly low. A little low? Dunno. I think it's a matter of finding just the right balance...and I don't think you can really say X% is good and X% is bad...That's why Dave says his cut chart is a guide...BUT, I can say that the pictures of your stone look amazing. An older fashioned style can still be a well cut stone, so it's going to have brilliancy!!! (like yours!!!) My guess is that It might be possible to anticipate how the stone is going to look in terms of facet placement and a general look I guess ...but can you predict how the stone is going to perform and if it appeals to your eyes? I would say definitely not. Fancy cuts are not that easy!!!
What I would actually do is have sent it to a GOOD appraiser and shell out some bucks to get some B-Scope. They will be able to interpret how a stone does...But I also think you can trust your eyes. What do your eyes tell you?

 

[moremoremore]

p.s. I can't believe that "my" cushion is on its way to hong kong for a jewelry show.

I picture it all packed and ready to go..it's tiny little brief case with GIA cert tucked neatly inside

In fact, it's no longer listed on blue nile.

 

[naomi]

thank you everyone.
Those infos are very very valuable in my tough but rewarding cushion search!

 

[valeria101]

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On 9/15/2004 8:36:28 PM cushioncut wrote:




is it possible to determine the look of the stone from what the plot looks like? It would be very helpful if you could.


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It would ... but you cannot. There is a limited number of stock pics that are matched to the stones but, obviously not intended to show what the actual diamond looks like. Those are more like maps to help you locate inclusions (they are inclusion plots after all).

The Gem Adviser (you can find examples of GEM files of cushion cuts on GoodOldGold) software recreates 3D images of stones from precise measurements, and GCAL certs show front and back pictures - those are the only ones that do show what the stone looks like, as far as I know

 

[moremoremore]

Oh Wow Ana, that is very interesting. I really did not know that they just used the closest stock pic for each stone. That does make perfect sense though!!!

 

[reena]

wow-that IS interesting. actually i had wondered, because while i was browsing for stones i noticed that often the plots didn't match the shape of the particular cushion i was looking at (ie L to W ratio seemed off).

 

[moremoremore]

I've found that the length to width is usually exaggerated. Like on a 1:06 princess I had...it was shown on the plat as completely rectangular...But I thought that the plot was for that particular stone. Duh.