CVD or HPHT Lab diamonds?

[secretagentdee]

Hi I’m considering buying a lab diamond and I read there are two different methods of making them. CVD & HPHT.

Is one way better than another in regards to quality and look of stone? Also does it effect pricing?

Thanks in Advance

 

[OcnGypZ]

Rough grown via CVD is more controlled - thus the ability to eliminate nitrogen - resulting in higher colors and Type IIa diamonds. In nature only around 2% of mined diamonds are Type IIa

 

[OoohShiny]

CVD can have issues with regards to 'stria' (layers) being inconsistent and creating issues with light transmission, IIRC - have a search for 'stria' on the forum search tool and some discussions should pop up Each stone needs careful analysis, but then that's no different to Mined stones, lol.

Things also get more confusing because some stones are CVD grown then HPHT treated - I'm not sure how they compare to HPHT-alone stones, but my understanding (which may well be wrong ) is that HPHT-alone stones aren't at risk of stria issues, so they are safer in that regard.

 

[alene]

Rough grown via CVD is more controlled - thus the ability to eliminate nitrogen - resulting in higher colors and Type IIa diamonds. In nature only around 2% of mined diamonds are Type IIa

I thought it was the other way around, no?

 

[OcnGypZ]

I thought it was the other way around, no?

That's the way it is.

 

[secretagentdee]

Thank you for your replies.

Would you notice these characteristics for an average consumer looking at the stone?

 

[alene]

That's the way it is.

Hmm, not according to these guys

https://betterthandiamond.com/pages/Lab-Diamonds-%2d-Facts-and-FAQ.html

 

[OcnGypZ]

https://www.gia.edu/identifying-lab-grown-diamonds This is best explanation I've read - from the GIA. Note, they've installed their own CVD technology to study Lab created stones.

 

[alene]

https://www.gia.edu/identifying-lab-grown-diamonds This is best explanation I've read - from the GIA. Note, they've installed their own CVD technology to study Lab created stones.

Thanks for the link! Looks like they’re saying that most HPHT diamonds are yellow and most CVD diamonds are brown and gray unless HPHT treated to be colorless. There was a discussion here recently about some HPHT diamonds being exceptionally white and nitrogen free, but it doesn’t seem common either: https://www.pricescope.com/community/threads/unique-characteristics-in-mmd.250194/

 

[OcnGypZ]

HPHT diamonds have never been nitrogen free. Only Type IIa diamonds are nitrogen free. These GIA writings are also fairly outdated due to the rapid advancement of CVD R&D. CVD appears to be THE preferred process of manufacturers.

 

[xxxxxx]

@OcnGypZ the question is why is it the preferred process? Because it's less stress for the producer and they don't care about stria as it doesn't impact the clarity grading?

 

[alene]

HPHT diamonds have never been nitrogen free. Only Type IIa diamonds are nitrogen free. These GIA writings are also fairly outdated due to the rapid advancement of CVD R&D. CVD appears to be THE preferred process of manufacturers.

Apparently, most colorless HPHT diamonds ( and they certainly exist) are Type IIa. Supposedly, CVD is the preferred price because it’s cheaper and easier. Though I’d like to have this verified by someone who’s not selling HPHT diamonds exclusively:

https://betterthandiamond.com/pages/HPHT-for-Diamonds,-explained.html

 

[HDer]

I think the current CVD vs HPHT debate is a bit meaningless. HPHT is technically the older technology, and was used mainly to first create industrial diamonds. The diamonds in the early HPHT tech were brown and not suitable for jewelry. CVD came along and got really good at creating yellow fancies and later started gem quality white diamonds, with some tint to them.

However, both of these technologies have gotten MUCH MUCH better in the recent years. So like any technology, what we really should be talking about is generations. A cheaper Russian producer might be on an older generation of HPHT that might have problems compared to a later generation of CVD or vice versa.

 

[Eellee44]

Apparently, most colorless HPHT diamonds ( and they certainly exist) are Type IIa. Supposedly, CVD is the preferred price because it’s cheaper and easier. Though I’d like to have this verified by someone who’s not selling HPHT diamonds exclusively:

https://betterthandiamond.com/pages/HPHT-for-Diamonds,-explained.html

Just chiming in here but if you look at vendors that sell CVD instead, they say the opposite to BTD.

I looked at the BTD lab diamonds when searching for mine and all I can say is they were selling one that looked like this ....
Needless to say I then started looking elsewhere.

ETA: CVD vendors talking about CVD vs HPHT
https://www.shiels.com.au/blog/luminare-diamonds-lab-grown-diamonds

https://www.lgdtrade.com/blog/guide-on-cvd-chemical-vapor-deposition-diamonds/

And vendor who seems to sell both types
https://www.mygemologist.com/learn/lab-grown-diamonds/how-are-lab-grown-diamonds-made/

 

[alene]

Just chiming in here but if you look at vendors that sell CVD instead, they say the opposite to BTD.

I looked at the BTD lab diamonds when searching for mine and all I can say is they were selling one that looked like this ....
Needless to say I then started looking elsewhere.

ETA: CVD vendors talking about CVD vs HPHT
https://www.shiels.com.au/blog/luminare-diamonds-lab-grown-diamonds

https://www.lgdtrade.com/blog/guide-on-cvd-chemical-vapor-deposition-diamonds/

And vendor who seems to sell both types
https://www.mygemologist.com/learn/lab-grown-diamonds/how-are-lab-grown-diamonds-made/

Thanks for chiming in and wow, what was the clarity of that BTD stone? I contacted them recently, but was told they can’t provide pictures of individual stones, which was a no go for me. They do seem to have mostly D color stones, but seems like clarity can be an issue. Thanks for the links also!

 

[Eellee44]

Thanks for chiming in and wow, what was the clarity of that BTD stone? I contacted them recently, but was told they can’t provide pictures of individual stones, which was a no go for me. They do seem to have mostly D color stones, but seems like clarity can be an issue. Thanks for the links also!

That one is a D I1 in their fairness.

I found it really hard to navigate their site and when I was searching I actually had no idea what the clarity was when I enquired because it wasn’t visible from the purchase page I was on which I found very odd, to be honest it almost felt like a trick.
I found this on the super ideal hearts & arrows page which they market as matching AGS-000 standards which is why I was rather shocked they were selling that particular stone when I received the photos. They did say it was priced “accordingly” (which to me is a bit of grey area when it comes to lab diamonds). From memory it was 2.5k. It also looked poorly cut to me.

I’m also very surprised they don’t send photos of individual stones because they did to me but also how can they expect someone buying something online is okay with purchasing something without seeing it first? Especially considering they have different clarities and colours etc?

 

[lovedogs]

I would avoid BTD. they aren't known for being super honest or upfront, and they often have misinformation on their website.

 

[whitewave]

HPHT is the better one to choose.

 

[lovedogs]

After listening to the speakers at the g2g, I feel like both methods are similar...the difference is more about the equipment and cost to the vendors. So I honestly don't think there's "better".

 

[Eellee44]

HPHT is the better one to choose.

Can you elaborate?

 

[lovedogs]

I think the current CVD vs HPHT debate is a bit meaningless. HPHT is technically the older technology, and was used mainly to first create industrial diamonds. The diamonds in the early HPHT tech were brown and not suitable for jewelry. CVD came along and got really good at creating yellow fancies and later started gem quality white diamonds, with some tint to them.

However, both of these technologies have gotten MUCH MUCH better in the recent years. So like any technology, what we really should be talking about is generations. A cheaper Russian producer might be on an older generation of HPHT that might have problems compared to a later generation of CVD or vice versa.

Exactly. Here's an explanation that I like from a vendor who seems to sell both. It's similar to rhe Wikipedia write up and is consistent with what the gia people told us at the g2g
https://www.mygemologist.com/learn/lab-grown-diamonds/how-are-lab-grown-diamonds-made/

 

[xxxxxx]

@lovedogs did the gia people also touch on the subject of stria in cvd dianonds? For me that's a big turn off on lab diamonds generally to imagine they were created inferiorly by "spray painting" one layer of diamond onto the next.

 

[OcnGypZ]

It's nothing like spray painting - however stria is not visible to the naked eye. They can only be viewed by using special polarized filters. They lost me with all their wave lengths, etc. I really did try to pay attention.

 

[xxxxxx]

Do I can disregard the following post
I mean that would be great if this "problem" wouldn't be as described.