Hacker News Reader

Comment by darksaints | Hacker News Reader

Sounds like prices for gem cut diamonds, which brings in the whole DeBeers monopoly pricing. I wonder why manufactured or rough cut diamonds couldn't be used.

View on HN

Having worked in materials science research, the problem is that you generally need a very bespoke specific thing crafted for you by a professional lab supplier, and that is expensive.

It is a diamond press, the diamonds have to be cut to shape and they also have to be transparent. Industrial diamonds aren't transparent enough.

Modern lab-grown diamonds are higher quality than even the finest gem-quality natural diamonds.

From what I understand, the issue with lab-grown diamonds is that they can't really grow them beyond a certain size at this time. I think clear ones are a couple of carats, and colored ones are roughly double that. I could be off a bit. Regardless, that's not huge, though I don't know what size they require. Maybe it's sufficient.

Why do the diamonds need to be transparent?

People interested in high-pressure chemistry follow what's happening with spectroscopy, UV/Vis or infrared. Fig. 3 on p. 376 has the Raman spectrum.

So they can probe/measure the contents with light, usually in laser form.

Contents are completely enclosed by diamond to hold the pressure. No way to probe otherwise as far as i know.

X-rays are also widely used to probe high pressure matter within diamond anvil cells

Here is an example at an ESRF beamline https://www.esrf.eu/home/UsersAndScience/Experiments/MEx/ID1...

Don't forget neutrons! Not as quick to measure, and not so good with very small samples, but well-suited to combinations of extreme environments beyond just pressure, such as temperature, magnetic field, voltage gradient etc. https://www.isis.stfc.ac.uk/Pages/Pearl.aspx

Amusing to see for an x-ray crystallographer that the neutron scattering coefficient for tungsten carbide is actually lower than for pure carbon. Neutrons are weird.

My hypothesis is that they have imperfections in them that lead them to be structurally weaker than ones crafted by the natural pressures of the Earth.

This is actually not true! This was was true maybe 15-20+ years ago but since then lab diamonds have gotten very pure. So pure that now Big Diamond markets their flaws as "natural characteristics" that make their diamonds unique.

Pretty funny if you ask me.

That being said, lab diamonds are not necessarily that cheap, depending on the dimensions and qualities necessary.

Yeah but they still have defects. There is no such thing as a defect-free material, it's thermodynamically unstable. Under stress, the defects (voids, dislocations etc.) lead to crack propagation and the diamond is kaput.

Distinguish "perfect" from "better than natural diamonds".

Lab-grown are better than natural in the sense that they have a lower density of defects. But they still have defects which means they will break under sufficient stress. It doesn't matter if the diamonds they source is lab-grown, it will still break under sufficient stress.

That's the thing, lab grown diamonds have fewer defects than natural ones. They're too perfect, according to the diamond/jewellery industry.

I'm disputing the notion that in order to prevent the breakage of the diamond anvil cells that the researchers used, they should source lab-grown diamonds. I'm saying that those will too break because they contain defects. Lab-grown is better, but still not defect-free.

Reply on news.ycombinator.com