Unique characteristics in MMD

by OoohShiny » Jul 17, 2019

Good to see some useful, detailed information being presented to enable informed buyer decisions although one could view the focus on potential negative aspects as dissuading customers from considering MMD generally

That is fine, though - there is a position for everyone in the market and it is good that CBI/HPD are setting out their stall clearly


I thought these bits were interesting:

https://www.hpdiamonds.com/en-us/extra/172

https://www.hpdiamonds.com/en-us/extra/173

Do we have links to the research that shows this? I like science so links/footnotes to Research Papers would be very welcome! (I do recall reading something about it on here but can't remember where now...)

Perhaps @Wink would consider adding footnotes that link to the GIA research papers or similar?

(I always think sites with clearly evidenced positions have much stronger arguments for their positions!)

 

by elle_chris » Jul 17, 2019

Ordered my Blue grown HPHT pear diamond. I knew about the inclusions being different (metal) and it makes sense but I honestly don't care. Especially since I purchased a VS1 so the inclusions are minimal.

But, I was considering a CVD round.
If the the reduction in fire, and brilliance is visible to the eye (I don't care about machines detecting it), then I wouldn't do it. I love diamonds for their brilliance, and fire, so this would be a deal breaker for me.

 

by Lessics » Jul 17, 2019

@OoohShiny this observation is very off putting and keeping me from going forward with a lab grown diamond purchase.


I just wish HPD would offer lab diamonds (obviously) without any upgrade possibilities that would be a dream.

 

by Matthewgolf34 » Jul 17, 2019

I purchased 1 cttw round earrings last December and recently a 1.24 G, VS2 and I disagree with this article's points that OOS brought up. If anything, I remember Garry Holloway coming back from JCK in May/June and commenting how brilliant the MMD diamonds were.

I am forever a skeptic in life and like OOS, I prefer science (rather than a vendor's opinions). If there is a difference in visuals like HPD brings up, it is very likely imperceptible to human eyes. I hear a lot of yapping in this space and not a lot of data to support the conclusions that many industry players have against MMD. If visuals are what are holding you back from a purchase, I have extreme conviction that MMD will hold up to natural after the science has been done.

If the value of your purchase eroding over time is holding you back, I think this is a valid point and I would only be willing to spend as much money as you are willing to lose on MMD. I still would argue buying a MMD is a better financial decision in many cases, but I digress.

Great article @kgizo! And thanks for pointing out the clips, OOS! I bet you the article is correct in its claims--albeit misleading. Wouldn't be surprised to see MMD perform 0.001-1% than equivalent natural diamonds. I also won't be surprised if natural diamonds run some study where they power it incredibly to show than natural diamonds have better optic qualities than MMD. Perhaps statistically significant but not relevant in real life. Just my two cents and I'll be honest I am simply speculating on much of this.

 

by OoohShiny » Jul 27, 2019

I managed to dig up the thread I was looking for re: layering in CVD stones!

https://www.pricescope.com/communit...en-natural-and-lab-grown.249513/#post-4561705

There's an example in there of a stone with what looks like layering, and I found this one today that I thought looked like it might have potential layering:
https://www.jamesallen.com/loose-diamonds/asscher-cut/1.27-carat-h-color-vs2-clarity-sku-7020926

It would be interesting if there was a way to quantify any potential impacts to 'crispness' from CVD layering. Perhaps the way forward is CVD stones that have also been treated with HPHT after creation, or perhaps purchasing HPHT-only stones only? I think both have potential issues that would need assessment, going from what I have read!

EDIT: I have asked the question in that thread

 

by Wink » Jul 27, 2019

Thank you for the compliments on the article on my website. @John Pollard composed the piece. He cooperated with GCAL, among others, to gather and publish some very exceptional images.

I have not seen such a concise and clear overview of the different processes as he outlines. The “carbon rain” explanation regarding CVD, along with those images of CVD rough before and after annealing are wonderful.

You can direct any follow up Qs to John. I know he has had the opportunity to immerse himself in this topic the past few years, and has gained hands-on experience with both types of synthetic production from various producers.

Wink

 

by whitewave » Jul 27, 2019

That James Allen one is a weird color to me. It says H but all I see is brown tint.

 

by elle_chris » Jul 28, 2019

I think it's the way they're being photographed.
Checked their natural H colored asschers and they all have a brown tint on my monitor as well.

 

by whitewave » Jul 28, 2019

Ok. Interesting. However, something to keep in mind is that GIA does not note brown tint on colors higher than I believe J and also that man made diamonds start off tinted brown and have to be bleached to become whiter.

At the end of the day, I guess you would have to see it in person.

 

by OoohShiny » Jul 28, 2019

I *think* that's only HPHT stones... but then HPHT is used to remove tint so I might well be getting confused...

 

by MrsChemist » Jul 31, 2019

I'm normally a lurker in the forums because I like seeing other people's shiny jewelry, but as a chemist with a PhD, I feel the need to question this and whether there is misrepresentation, and what exactly they mean by "stria".

The way carbon crystallized depends on whether you're getting pencil graphite or a diamond. That means that in order for a diamond to form, carbon would need to grow in a cubic crystalline shape. I am unclear what the vendor is trying to get at when they say the layers of stria are different, because if carbon is NOT forming cubic crystalline structures, you would obviously not be getting a diamond. Now, with the imperfections seen in diamonds, that can be due to the fact that the diamond crystal lattice is not completely continuous through the entire stone, but I have no clue how this leads to a completely different stria when at the most basic form, diamonds are a carbon cubic crystal lattice structure.

Also, I am fortunate enough to live near a physical Brilliant Earth store so I was able to make an appointment and compare the visuals between a lab and natural diamond, VS2, I color, Super Ideal cut (according to BE, so basically GIA's equiv of Ideal), as my husband and I were buying a new ring since I wanted to upgrade to a 2+ carat round from the 1 carat princess I originally had. The lab diamond (graded by GCAL) actually looked a little whiter to me than the mined diamond (graded by GIA). Not wanting to be influenced by my own biases, I asked them to not tell me the specifications until I had examined them first. Based on what I know, lab diamonds sometimes can have boron impurities, instead of nitrogen impurities, which are in mined diamonds. The boron impurities can cause a bluish tint, causing the diamond to face up more white, where as nitrogen impurities cause the yellow tinting (I also know this from my research, but it was nice that I can self-verify they weren't bullshitting me).

I ended up going with the lab diamond and I don't regret it as when I buy jewelry, I buy to keep, not to resell later. If resell value is important then I would go with mined, but even then, I'd shop around, as my original mined diamond can't even sell for half of what my husband originally paid for it (we're keeping it as it has sentimental value). Hubs was also happy I decided to go with the lab instead of mined since we are both scientists and are supporting the scientific industry. Also, my 2.3 carat lab round sparkles a lot more than my 1 carat princess, but that could be due to cut.

Anyways, for people looking into getting diamonds, definitely do thorough research, not just from what vendors say about them, but actual scientific articles, and try to learn as much as you can. At the end of the day, the diamond industry is a lucrative one, and no one is going to be looking out for your own interest except yourself. Also, I would highly highly recommend seeing the stones in person, since the location and types of inclusions can cause visual differences.

 

by denverappraiser » Jul 31, 2019

Nice article John.

I must admit, my favorite line is this reference to HPHT:

"A carbon source, a diamond seed, and a metallic catalyst go into an octahedral cell."

I'm not sure what the punch line is but I'm already laughing.

 

by John Pollard » Jul 31, 2019

Thanks @denverappraiser

How about this attempt?

"A carbon source, a diamond seed, and a metallic catalyst go into an octahedral cell."

The diamond seed asks the carbon - What are you in for?
- Carbon says... 'Dating too young.'

He asks the catalyst 'What about you?
- Catalyst says... 'I had a meltdown'

Diamond seed says 'Who can blame us? We're all under a lot of pressure.'

 

by John Pollard » Jul 31, 2019

Regarding the appearance questions above, I’m the author of the article linked in the original post. Thank you @kgizo for the link.

I will be happy to provide more details regarding my personal experience:

As with mined diamonds, the quality of rough material can cause perception of undertone. This is well documented. On a more nuanced level it can also influence the perception of material transparency and optical performance qualities. This is less documented (and remains a long standing thorn in the paw of natural diamond assessment btw).

Some synthetic diamond producers are exceptional. There is one HPHT producer who has spared no expense to eliminate nitrogen; to the insane degree that experts declare certain of their output “C or B” in color (meaning higher than D). I’ve seen this and it’s absolutely true. The material has a subtle blue undertone but is exceptional in its whiteness. Very special.

Then you have the other side of the spectrum. As more players enter the game it’s inevitable that human-produced synthetic rough output becomes more variable. This is exaggerated by entities who are entering the fray with less resource, lower quality equipment, presses converted from industrial use to GQ, contamination confounders, etc.

My personal experience? The polished laboratory-grown diamonds I’ve seen with muted performance qualities were exclusively HPHT annealed CVD output. The samples were all similar: A casual gemologist might consider the deficits as surface-polish issues. It’s worth noting that CVD is far more challenging in cross-working and brillianteering than HPHT rough. Honestly, its a PITA to cut. So polish challenges do come into play. But there is a direction and depth to the visual muting (the term muddying is also used - not my word) which goes deeper than surface polish.

Where will you see it? No idea. This is a new frontier and the results are producer dependent. If you’re looking at production from a top producer the output may be fine, compared to fly by night operations surfacing in China, more focused on spamming your inboxes than refining their output.

@OoohShiny you mentioned a desire to see research on the CVD topic by GIA. I'd love to see a study as well. But please keep in mind that many industry pros have been asking them to address the topic of transparency at-large for decades, as well as the impact of tint/haze beyond 10X in naturally formed diamonds. The impression I get is these topics are a Pandora’s box they prefer not to open.

For what it's worth, GCAL as a proactive lab, or DeBeers' as a knowledgeable producer, may be best positioned to publish such studies (ymmv with DeBeers').

Absolutely. This is the advice I'd give to anyone considering a purchase. There is no substitute for the in-person experience. Really, no different than seeing and comparing natural diamonds in person.

I hope the above is helpful.

 

by OoohShiny » Jul 31, 2019

Thank you as always for your detailed input, kind sir!

This sounds very intriguing!!

This is all very interesting stuff, thank you! Would you say that the direction/depth of visual muting issues tends to be parallel with the planes/layers of the stria? I can sort of visualise that perhaps layers end up looking like stacked glass sheets - see-through with a bit of tint from the 90-degrees direction, but viewed side on they are often a much darker colour and/or opaque?

That may be complete nonsense, of course lol

I am surprised that it is more difficult to cut, though - my gut instinct is that a more uniform structure/'grain' would be easier to cut, give it could be easier to predict and plan around than the (I assume) random 'grain' of a Mined diamond that could be squashed in various different directions! (Is the reason that Yoram notes that the Argyle rough is much trickier to work because it has suffered plastic deformation and therefore has a more complex grain?)

I think you may be right...

 

by Lessics » Jul 31, 2019

@MrsChemist Thank you for sharing your experience!

Did you look at several lab diamonds? And do you know if your dianond is an cvd or hpht grown diamond?

 

by MrsChemist » Aug 1, 2019

Hi Lessics, hoping that some people may find my experience useful since some people don't have access to the same resources (ie being able to see a lab diamond IRL). Keep in mind though that this is just my own personal experience, so I like to always tell people to do your own due diligence when buying diamonds, either mined or lab grown, as everyone's experience may be different!

My diamond was grown by the CVP method according to the GCAL cert that I received. I had originally wanted one that was a HPHT method given that it tries to replicate the pressure and temp of earth's conditions of growing diamonds (minus the time), but a lot of the lab diamonds that I was viewing on BE's website was the CVP method, so I decided to just go in and take a look. I actually made a couple of appointments with BE to view the diamonds in person. My first appointment I was deciding between mined and lab, and the second appointment, I was deciding between the colors. I'm slightly color sensitive, as I could see the difference between E and H, but I wasn't really able to tell the difference between H and I. Also, I think the lighting conditions in BE are not the best conditions, because after I received my diamond in the setting, I remember thinking that the diamond looks whiter out in the world than when I saw it in the showroom. I was also only considering diamonds that had the "super ideal" cut on BE, which is basically "ideal" for GIA or GCAL, which may or may not make a difference in how white the diamond looks. I haven't done enough research into that, and tbh, don't have the time nor interest, as I prefer to make a judgement after seeing it in person. That's why i champion seeing diamonds in person if you can, or if not, make sure the store has a really good return policy.

Also, I think BE might be a little more expensive then other online only retailers, but don't quote me on it as I haven't been looking recently and I bought mine last year. I was ok with it since that extra cost allows me to request to see the diamonds in person and a sense of security. You never know how accurate the monitors are, and I don't like the hassle and stress that would come with shipping a diamond. Plus, they gotta cover the cost of retail space somewhere.

I'll try and provide some pictures tomorrow after I get home from my vacation tmrw.

 

by MrsChemist » Aug 1, 2019

This is in the bathroom with warm fluorescent lighting.


This is in the car on an overcast day.

Also the specs are: 8.45mm, I color, VS2, Ideal Cut GCal cert.

Since I know that some people are concerned about the sparkle of lab diamonds, I also have a video on my phone where I tried to capture the sparkle in bathroom lighting but I can’t upload it here. Any good upload sites besides imgur since I am on mobile?

 

by whitewave » Aug 1, 2019

I upload on IG and then give my user name for people to find. We aren’t supposed to upload videos here.

 

by Lessics » Aug 1, 2019

I uploaded videos to my youtube account but only made them accesable via a link so they weren't really published to my account.

Thank you for sharing the pictures. It's a beautiful ring!

 

by John Pollard » Aug 1, 2019

You're quite welcome. And yes. It's fascinating.

I'm not sure the photo properly shows the nuance, but one example of 'special' D on left, natural D on right.

No and yes. I never saw variation in material transparency due to angle of observation. I was only looking from top-down assessing performance qualities. In slight cases it presents like double refraction (think faceted calcite). Beautiful performance when well-cut but slightly off from diamond. In more pronounced cases there's muting, resembling natural diamond where one side didn't take a good polish. The first reaction is to grab a microfiber cloth and "fix it."

I'd start with this... No diamond is "easy" to polish. It's hard. It's stubborn. It fights. It doesn't want to be polished. It was perfectly happy like it was.

That's the reason the earliest cuts essentially followed the outline of octahedron and dodecahedron and twinned/flat crystals (rose cut for the latter).


Credit: Erstwhile Jewelry for the nice graphic.

Yes, Argyle rough has more twinning and structural defects than other primary souces. That's why we get more pink and red FCD from Argyle, by the way.

With all that said, for better or worse, our plans, tech and tools were developed to follow the essential shape of natural octahedron or dodecahedron. So when we introduce material which grew in vertical layers there's a learning curve. It may not be physically 'harder' but it's a new frontier.

You cause me to wonder though. It may be easier to polish CVD that isn't annealed to bleach the color (left) than HPHT-annealed material which goes through another phase (the two cubes top right). I can ask about that.



Here's a decent explanation and animation of CVD growth.



And I love this video. About 1 minute in you'll see the intense process used to take a rough cube to a more viable semi-polished state where it may find its way forward with traditional girdling, blocking and polishing tools.

https://www.adadiamonds.com/cvdgrowth

Can you imagine leaving so much natural rough on the cutting room floor?

Of course if the earth had given us cubed rough the round diamond wouldn't have evolved. Too much waste. Preserving shape and weight would mean a world of shallow emerald cuts, maybe with some pesky radiant and princess concepts popping up here and there if someone thought kite-shaped facets would be groovy.

Interesting footnote: Because of its layered growth, it's not interesting to cut steep-deep from CVD.
Cue applause.

 

by MrsChemist » Aug 1, 2019

@whitewave and @Lessics thanks for the suggestions, I ended up creating a new Instagram account and posted the video there. If anyone is interested in seeing the diamond under bathroom lighting my insta is Dr.Chemist9. It was difficult to capture the sparkle, as my ring sparkles more in person than in video. I’ve also noticed that my diamond is super sparkly in elevators, at the mall and in sunlight, but it’s soooo difficult to capture. Hoping it helps.

 

by whitewave » Aug 1, 2019

Thanks for doing this. Diamonds look best in a video in sunlight but under a tree canopy with leaf shade and sunlight passing through. My videos are under yatcube— no MMD though. I was taking a video of my aquamarine and in the video I say “aww the sun just went behind a cloud” lol. And wal mart, sams, Home Depot are the best places to take a video.... lighting department at Home Depot or Lows lol

 

by OoohShiny » Aug 1, 2019

Cool! Thank you for posting the pic

I think I can see a slight difference - camera settings and monitor settings always do their best to sabotage us!

Do we know if the 'D+' diamond has any nitrogen or boron or vacancies in the structure? I guess I'm wondering what colour (if any) a '100% pure' diamond, with a perfect structure and nothing but carbon in it, would be!

(And I want one for the technical achievement and coolness lol)

A good reminder on the difficulty and history of cutting diamonds, though, thank you - I think it is easy to slip into the mindset that it is 'easy' (and even more so with blocking machines and MMDs, whether correct or not!) to cut diamonds

I'm happy that my questions aren't all totally annoying lol

This might be another daft one, though... ... but would it be possible to swap the process round and apply HPHT treatment after blocking, girdling and initial polishing, if it meant that those stages were physically less demanding with CVD-alone MMD rough? Leaving final polishing to be done after HPHT?

(I know we're talking High Pressure High Temperature, but is the High Pressure bit created by the growing machines actually *touching* the MMD rough? Or is it a similar volume chamber to CVD-rough creation and the atmospheric pressure increased substantially? If the latter, it would seem that swapping the stages around as suggested would not be impossible??)


I can't see that Ada Diamonds site on this computer (I imagine it needs Chrome or something else other than ageing Windoze IE ) so will see if I can get to another screen that it works on, thank you for the link!

 

by elle_chris » Aug 1, 2019

There's a big difference between the diamond on the left and the diamond on the right. The right ones almost look cloudy compared to the left which looks crystal clear and just slightly blue on the tip.

 

by elle_chris » Aug 1, 2019

Beautiful ring!
I can't find you on insta. Dr.Chemist9 isn't coming up.

 

by whitewave » Aug 1, 2019

I found you. Diamonds need light, so at some point, find the brightest light you can (cars and fluorescent light is terrible for pics and videos) and take a new video.

You want sunshine, or white led lights or by a window on a bright day etc.

 

by MrsChemist » Aug 1, 2019

Thank you! That’s weird. I wonder if lower and uppercase matters? My instagram is dr.chemist9 and whitewave was able to find me.

Thanks unfortunately the sun is not out today! It’s pretty gloomy and cloudy, so I snuck into the elevator at work and luckily no one was there and got a video which I posted on my IG. My iPhone camera still isn’t capturing how sparkly it looks IRL, but the elevator lighting shows how sparkly it is over my earlier bathroom lighting. I’ll try and get a sunny video sometime. Hopefully this helps people make informed decisions. During my buying process I didn’t feel like there was an observable difference between lab and mined (at least to the human eye), as I was comparing diamond with very similar specs, although the grading reports were diff as GIA does not have substantial details for lab diamonds.

 

by Lessics » Aug 2, 2019

@John Pollard Thank your for sharing this information.

Are you allowed to disclose the company that makes these better than D lab diamonds?
And wouldn't one buy a moissanite if lab diamonds had a double refractive index or a higher refractive index compared to mined diamonds?