Do all CVD diamonds having straining - including “single growth” or “slow growth”?

[skim]

I understand CVD’s have (or can have?) straining problems, and it seems obvious to spot on poor quality diamonds. But what isn’t clear (at least to me) is what a really good CVD looks like - should it have no straining or is a little bit considered normal / acceptable (ie negligible on performance).

Maybe said another way: is a certain level of straining expected (ie an unavoidable characteristic of CVD) and even the best quality examples of CVD have it?

This image is of presumably a high quality CVD and I assume this is showing some “minor” straining? This is from a “single growth” CVD process. I’m not sure if that is the same as “slow growth”. I couldn’t find a specific example from that growth method.




Additionally, here is an image and video of another CVD that I assume is “high quality” (not documented as “single growth”, but presumably had post growth treatment. I read post growth treatments can make diamonds less optically clear in a different way? I don’t know if that makes some of the subtle straining less visible overall.

Gem360 - M4588

ID: M4588, Size: 2.02, Shape: Round

view.gem360.in

 

[Texas Leaguer]

Strain and striation, both forms of disruption in the normal growth of diamond crystals, can occur in both lab grown and natural diamonds. It is most closely associated with CVD growth because the technology allows an operator to monitor progress and to stop and start the process to make adjustments or corrections. This causes fluctuations in the growth environment and can lead to these problems.

Transparency, like virtually all aspects of diamond quality, is a matter of degree. Diamonds with significant striation will be less transparent and will not be capable of optimal light performance. But the same is true in natural diamonds due to clouds, graining, twinning, fluorescence, etc., if any of those features (or combination of features) appreciably impacts the propagation of light rays through the material.

Unfortunately, laboratory reports do not directly measure transparency. There are certain items to look for on a report that are red flags for this problem when it is severe. Otherwise, you just have to carefully inspect the diamond to determine if there is a material deficit. This is where dealing with a merchant with experience and expertise becomes very important as meaningful transparency issues can be very subtle and require a trained eye.

 

[skim]

Thanks. I understand what you are saying with regards to the “stop and start” process, which is linked to making the straining worse.

I’m specifically trying go understand if straining is an inherent / unavoidable characteristic of CVD. I’ve looked at a couple of videos of D IF CVD and it still seems visible under magnification. Note: The first image is of a CVD from a “single growth” lab, not IF, but light performance received high marks.

 

[skim]

Unfortunately, laboratory reports do not directly measure transparency.

Is this different than optical brilliance that GCAL 8X measures? If so, what is the technical and practical difference?

 

[0-0-0]

There are CVD diamonds with negligible straining that look as clean as HPHT diamonds.

Straining in both lab and natural diamonds don’t affect the clarity or light performance grades from GIA/AGS/GCAL.

 

[skim]

There are CVD diamonds with negligible straining that look as clean as HPHT diamonds.

Straining in both lab and natural diamonds don’t affect the clarity or light performance grades from GIA/AGS/GCAL.

Thanks. Would you consider any of the above examples negligible? Or can you find / post an example that is as clean as an HPHT?

Straining is new to me. I was somewhat familiar with graining on natural diamonds which AIUI does affect clarity grading.

My personal impression is that straining does appear to objectively affect clarity and some aspects of light performance. For instance it is scattering light to some degree similar to how a matte finish works on glass. Also the flashes of color appear to be more of a gradient vs solid appearance. Presumably to get solid color reflections off a facet, it requires a perfectly flat mirror like finish. Is there a reason why these outcomes are not considered with grading?

 

[Texas Leaguer]

Is this different than optical brilliance that GCAL 8X measures? If so, what is the technical and practical difference?

You can contact GCAL for verification, but I don't think their methodology accounts for variations in transparency. Nor does ASET or IdealScope.
Those tools give you a view of the structure of light returned, which of course has a major impact on performance.

Technically, any inclusions (and even amounts of body color) can reduce transparency (it's a matter of degree). This is apparently why developing a metric for transparency for a lab report has been such a challenge. I have been told by someone in one of the top tier laboratories that they are actively working on this problem, and I have advocated for this for many years, as I think it is a major blind spot for consumers.

I will be delighted to see a valid system (even if not a perfect one) rolled out to elevate awareness and give consumers more information about the role of transparency in light performance. This is particularly important to the growing number of diamond shoppers focused on cut quality as a means to obtain high end performance.

 

[Texas Leaguer]

Thanks. I understand what you are saying with regards to the “stop and start” process, which is linked to making the straining worse.

I’m specifically trying go understand if straining is an inherent / unavoidable characteristic of CVD. I’ve looked at a couple of videos of D IF CVD and it still seems visible under magnification. Note: The first image is of a CVD from a “single growth” lab, not IF, but light performance received high marks.

Since we deal primarily in HPHT at this point in time I don't really know how common strain is in CVD, or whether it is somehow inherent in the process. I would not think it would be.

 

[0-0-0]

Thanks. Would you consider any of the above examples negligible? Or can you find / post an example that is as clean as an HPHT?

Straining is new to me. I was somewhat familiar with graining on natural diamonds which AIUI does affect clarity grading.

My personal impression is that straining does appear to objectively affect clarity and some aspects of light performance. For instance it is scattering light to some degree similar to how a matte finish works on glass. Also the flashes of color appear to be more of a gradient vs solid appearance. Presumably to get solid color reflections off a facet, it requires a perfectly flat mirror like finish. Is there a reason why these outcomes are not considered with grading?

Examples of really nice CVD

Gem Certification & Assurance Lab

www.gcalusa.com

Gem Certification & Assurance Lab

www.gcalusa.com

Examples of GIA D IF natural diamonds with graining/straining that likely affect transparency

1.00 Carat round diamond

This 1 carat round diamond D color if clarity has Excellent proportions and a diamond grading report from GIA

www.jamesallen.com

1.05 Carat round diamond

This 1.05 carat round diamond D color if clarity has Excellent proportions and a diamond grading report from GIA

www.jamesallen.com

1.05 Carat round diamond

This 1.05 carat round diamond D color if clarity has Excellent proportions and a diamond grading report from GIA

www.jamesallen.com

 

[skim]

Examples of really nice CVD

Gem Certification & Assurance Lab

www.gcalusa.com

Gem Certification & Assurance Lab

www.gcalusa.com

Examples of GIA D IF natural diamonds with graining/straining that likely affect transparency

1.00 Carat round diamond

This 1 carat round diamond D color if clarity has Excellent proportions and a diamond grading report from GIA

www.jamesallen.com

1.05 Carat round diamond

This 1.05 carat round diamond D color if clarity has Excellent proportions and a diamond grading report from GIA

www.jamesallen.com

1.05 Carat round diamond

This 1.05 carat round diamond D color if clarity has Excellent proportions and a diamond grading report from GIA

www.jamesallen.com

Thanks for the examples of the clean CVD’s. I agree the straining on them are really difficult to detect (or maybe it’s not even present and what I’m seeing is an artifact of the videography or something else). Perhaps the best conclusion at the moment is that there are likely to be examples of a “perfect” CVD that doesn’t have straining, but are few and far in between.

The D IF examples further support what is being said, which seems to be:

• It’s present in even the “best” graded examples (ie doesn’t appear to affect grading)
• It doesn’t seem to be measured / accounted for (ie effect on transparency?)

 

[0515vision]

@skim what gives you the impression that clean CVD is free and far between? I know ppl skills be on the lookout for it with CVD, but to me “free and far between” feels a bit overstated.

 

[skim]

@skim what gives you the impression that clean CVD is free and far between? I know ppl skills be on the lookout for it with CVD, but to me “free and far between” feels a bit overstated.

My impression / conclusion was born from my recent personal experience of looking through probably multiple dozens, if not hundreds of examples of LGD. (I’m sure others have looked at more.). All or nearly all showed some degree of straining - hence the topic question.

To be clear, I’m not suggesting or equating that CVD w/ straining are necessarily “bad”. That is what is expressed in a lot of marketing and or social media chatter, and I’m not echoing that. I think it is a judgement call on how it may or not objectively affect performance, as well as personal opinion on what is best / acceptable for them. For example a few years back a mined G SI1 was perfect for me - inclusions et al.

You are entitled to your opinion about “overstatement”, but I’m not aware of any measurable data to support any position. I’m expressing my opinion based on my experience and though I recently picked a HPHT, I have not written off CVD’s - either as a pairing or to acquire a completely different set.

Informally, if I asked someone to curate a list of a dozen “clean” CVD’s without any signs of straining - how long would that take? How many total CVD’s would they have to look at to get this list of a dozen? (I personally found zero.)

 

[0-0-0]

Keep in mind that the best diamonds, both natural and lab, are sold by vendors who carry them in house. The diamonds available on virtual inventory lists are typically the rejects or excess production that vendors don’t want to carry in house. Searching for well cut clean CVD or HPHT without blue nuance on shared virtual inventory lists will give the impression that they are rare.

 

[skim]

Keep in mind that the best diamonds, both natural and lab, are sold by vendors who carry them in house. The diamonds available on virtual inventory lists are typically the rejects or excess production that vendors don’t want to carry in house. Searching for well cut clean CVD or HPHT without blue nuance on shared virtual inventory lists will give the impression that they are rare.

No offense, but that argument is a FUD argument that is typically used by sales / marketing. Your argument rests on the notion that a select few vendors have a private supply so vast as to significantly distort the actual total world supply of clean CVD’s.

How many vendors cater exclusively to the niche market of “clean” CVD’s? How many of them are fully integrated that they have their own lab or own the intellectual property / patent to produce these?

I won’t name vendors, but I checked the images / videos of CVDs of the well known high end vendors - and while some are very faint, and others not, the CVD distinguishing feature seems present. (Ie not “clean”).

Again the argument isn’t that straining on CVDs are “bad”. It’s the question of whether it’s a practically unavoidable characteristic based on current technology and or economics that only a select few examples are possible. (Ie rare).

 

[Karl_K]

All diamonds have crystal defects period, its a fact.
The question is how often that rises to be a real world eye visible problem away from the microscope/camera.
That it is more common for it to reach that level in cvd is likely true.
There is a huge range of cvd crystal quality on the market from total crud to excellent crystal.
On the lists where everyones production is mixed you may see video for 10 stones all from one producer and draw a false conclusion about all producers.

There are a lot of things that can give a false view of having crystal issues in the consumer video.
These range from oil on the stone to DOF/focus issues of the video setup.
I look at them from multiple tilts to get a better idea of whats going on and in some cases its just inconclusive.

 

[PinkAndBlueBling]

Keep in mind that the best diamonds, both natural and lab, are sold by vendors who carry them in house. The diamonds available on virtual inventory lists are typically the rejects or excess production that vendors don’t want to carry in house.

Yikes! I'm not too thrilled by this, as I hate to think the HPHT I'm anxiously awaiting was some reject.

 

[0-0-0]

No offense, but that argument is a FUD argument that is typically used by sales / marketing. Your argument rests on the notion that a select few vendors have a private supply so vast as to significantly distort the actual total world supply of clean CVD’s.

There are many more than just a select few vendors selling diamonds online. The majority of diamond sales still occur offline, and most diamonds don’t get listed online with videos. Manufacturers sell directly to vendors first before listing the rest on shared lists. It’s anyone guess what the vendors buy, but I would expect them to avoid the lower quality goods, such as CVD with visible issues, that would not sell as quickly. The diamond videos we get to see online are only a tiny fraction of the market. It’s not possible to get a sense of how rare clean CVD is if we only get to see a tiny snapshot of the whole picture.

It’s the question of whether it’s a practically unavoidable characteristic based on current technology and or economics that only a select few examples are possible. (Ie rare).

That is a question that only CVD manufacturers can answer, but I bet it’s not an answer they would willingly or accurately give in order to protect their margins. All we know for certain is that it is costlier to produce cleaner CVD, and it is in the manufacturers’ interests to produce as cheaply as possible as long as the market will buy what they produce.

 

[0-0-0]

Yikes! I'm not too thrilled by this, as I hate to think the HPHT I'm anxiously awaiting was some reject.

It can simply be excess production too. I wouldn’t worry about it as long as it checks out in person.