Shallow crown and chipping risks...

[Laila619]

Hi everyone,

Experts, is it true that a shallow crown is more prone to chipping? Why is that the case? I mean the mechanics behind it--what would make a shallow crown more likely to chip? Would you personally avoid buying any stone (whether diamond or colored stone) with a shallow crown? Thanks so much!!

 

[ChrisES]

My understanding is that a shallow girdle is a chipping risk, simply because the extremity of the diamond is exposed. But obviously you are a more experienced PSer than me, so I will defer to the experts.

 

[Laila619]

My understanding is that a shallow girdle is a chipping risk, simply because the extremity of the diamond is exposed. But obviously you are a more experienced PSer than me, so I will defer to the experts.

Thanks. Yep, really thin girdles are definitely more prone to chipping. But on one of the PS tutorial articles, it said that stones with shallow crowns are also more prone to chipping, and I know I must have heard that before on the forum, so that's why I asked about it. But I'm just not sure what it is about shallow crowns that actually makes them vulnerable.

 

[ChrisES]

My understanding is that a shallow girdle is a chipping risk, simply because the extremity of the diamond is exposed. But obviously you are a more experienced PSer than me, so I will defer to the experts.

Thanks. Yep, really thin girdles are definitely more prone to chipping. But on one of the PS tutorial articles, it said that stones with shallow crowns are also more prone to chipping, and I know I must have heard that before on the forum, so that's why I asked about it. But I'm just not sure what it is about shallow crowns that actually makes them vulnerable.

Hm, the only thing that comes to mind is that the thinness of the girdle itself is just the absolute extremity of the diamond, but the thinner the angles coming off the girdle the more gradually the diamond thickens, while the bigger the angles the faster it thickens.

But this is the first I've heard of it being an issue, so I'd be very curious too, seeing as I own a shallow crown stone.

 

[oldminer]

A diamond with a shallow crown angle, less than 30 degrees, with a thicker girdle is likely to get little nicks and tiny chips over time which are no big deal. Combine a shallow crown angle with a very thin or extremely thin girdle and you vastly increase the chance for a far more damaging chip, larger nick, cleavage or a facture which can compromise the whole stone on occasion. Usually, the damage a person gets in normal wear is not a complete loss of the diamond, but it can be a major problem requiring substantial weight loss and a major cutting cost.

Diamonds are vrey durable, but brittle and you can chip and cleave them, especially if they have a weak zone. We don't see lots of damaged diamonds, but when it happens, you can certainly undrestand the sentimental attachment issues that can't ever be fixed.

 

[Laila619]

A diamond with a shallow crown angle, less than 30 degrees, with a thicker girdle is likely to get little nicks and tiny chips over time which are no big deal. Combine a shallow crown angle with a very thin or extremely thin girdle and you vastly increase the chance for a far more damaging chip, larger nick, cleavage or a facture which can compromise the whole stone on occasion. Usually, the damage a person gets in normal wear is not a complete loss of the diamond, but it can be a major problem requiring substantial weight loss and a major cutting cost.

Diamonds are vrey durable, but brittle and you can chip and cleave them, especially if they have a weak zone. We don't see lots of damaged diamonds, but when it happens, you can certainly undrestand the sentimental attachment issues that can't ever be fixed.

Thanks, oldminer! Can you explain why the shallow crown is more likely to get dinged? Is it just because it's thinner/weaker, as there's less 'material' so to speak? Or is it because shallow crowns generally come with shallow girdles?

 

[ChrisES]

Or is it that crown facets are always more vulnerable and in a shallow crown they are more exposed due to meeting the table at a shallow angle?

 

[oldminer]

A shallow angle meeting the girdle poses a chipping risk due to the crystal structure of diamond.

A shallow angle combined with a very thin girdle adds an additional element of risk because the thin zone near the edge is just more delicate than at a thicker place.

One sees chipping of 90 degree thin, pointy corners of princess cuts, points chipped on pear and marquise shapes. The thinness combined with shallow angles creates issues of durability that insurance covers. As a side issue, since insurance is at a flat rate, it is a better deal to insure riskier stones as the cost is not more than for virtually risk free stones.