How Shallow is "Very Shallow"? Do Diamonds Chip?

[NYDiamond]

Based on the statement below, how shallow is "very shallow" and might a concern regarding chipping of the stone.

"An even more serious aspect to a shallow cut diamond is the increased probability of chipping. The more shallow a diamond is cut, the sharper its outside edge, and the greater the risk of chipping. If a very shallow cut diamond is set into a ring and worn normally, it will chip. The question is not if chipping will occur, but how soon it will occur. On very shallow diamonds, chipping frequently will occur within a year of acquisition."

 

[barry]

On Round Brilliants:
Crown angles < 30 deg and Pavillion angles < 40 deg.

On Fancies:
Crown angles < 30 deg and Pavillion ang. < 35 deg.

Barry
www.superbcert.com

 

[Mara]

NY--where did you get that posted snipped of quote? I'd be curious to read it.

My stone is considered shallow, crown angle of 29.9 degrees. Upon talking to my jeweler (who loved this stone above the other one he brought in for us, both were priced the same so it wasn't as though he was trying to sell us one over the other), he said in his 30 years he had not seen a stone such as this chip unless it took a seriously hard knock in the right place (and that can happen to almost any stone if the knock is hard enough and in the 'right place'). So for him the probability was not high. Also, we asked our independent appraiser about it, and she has been in the industry for 25+ years and in the appraisal biz for about 10 and is very highly regarded in those circles, teaches appraisal classes for GIA etc. She said she didn't see that as a problem at all with this stone.

We insured the stone and put it into an exposed 4 prong setting. The crown angle is 29.9 and the girdle is thin-med. Maybe not the best combo when in a setting such as this, only time will tell!

I think it's also important to note that our appraiser told us that she sees most diamonds chip slightly over time. If you wear a ring daily for 20 years, the stone will have small nicks in it most likely around the girdle as that is the thinnest edge. These probably won't be visible to your eye. So unless your stone has a thick girdle, chances are any other stone would see some wear and tear over the years. That put it in more perspective for us.

We don't worry because it's insured and we love the stone.

 

[NYDiamond]

Mara:

It came from crossjewlers.com "How to Buy a Diamond".

We are looking at a 2.41 carat stone that spreads to a 3 carat. It has a shallow total depth of 4.26 mm and a depth % of 55.8. One of our concerns was it's potential for chiping. Don't have any of the other measurements but obviously also concerned about the optics.

 

[Mara]

Wow that is a huge spread! Make sure it doesn't have a fisheye. My stone is a 1.23c and spreads to 1.35c. Your spread sounds very big, a little worrisome since you must be sacrificing tons of depth to get that spread. A depth of 4.26 is similar to what a 1.25c should have...that is a huge difference. My depth is only slightly shallow...it's 4.08 when it should be more like 4.20, your depth is extremely shallow.

I would be very cautious about this stone. I am a fan of shallower stones with spread if you find one that is beautiful--but this one sounds a little fishy? I would definitely get more specs, get a copy of the cert and also crown and pavilion angles. The HCA may not recommend you purchasing if it is TOO shallow and that would be something I would pay attn to.

Please post more information when you can and before purchasing the stone. Girdle? Dimensions? Crown and pav angle? Table%? This stone IS a round brilliant right? Is it a modern round brilliant cut or an older style? I bet the table is huge!!

 

[NYDiamond]

Mara: It's an Oval, below is the info from the GIA cert.

2.41 Oval E/VS2
11.61 x 7.64 x 4.26
Depth 55.8
Table 60
Girdle Med to Thick
Polish VG
Symetry Good
Medium Blue Fluor.
L/W Ratio 1.52

I'm obviously concerned about the depth, any insight you or anyone else could provide would be appreciated. Unlikely I will be able to get angles.

Thanks.

 

[Richard Sherwood]

Are you able to get a good photo of the diamond?

Face up view and side view maybe?

 

[Mara]

Oval makes more sense than RB!

I can't be of any help with fancies, but I will plug the #'s into the AGA and see what it says. Maybe one of the experts can advise. See if you can get pix as Rich asked.

** Ran it through the DIY Cut Grader at AGA and it got all 1A's (very good!) and the depth was noted as 3B. The range is 1A-4B with 1A being a cream of the crop type stone and 4B being your average crappy mall cut. Of course there was no crown angle to compute...but those are the numbers as listed. Not bad! **

 

[NYDiamond]

Richard, Mara & Barry: Thanks for all of your info. Unfortunately we are not dealing with a very cooperative dealer. Additional information is probably not forth comming. We will probably pass on this diamond for a more conventional cut, unless we can get a sarin and or other information before hand.

Thanks again.

 

[Richard Sherwood]

If he's not cooperative, I'd pass on him too.

There's plenty of dealers that would bend over backwards to make a customer out of you.

Have you tried any of the regulars on the forum here? It would be pretty tough to find a better group of dealers (and personalities) than these guys. A very safe microcosm of the diamond world in which to shop.