It’s been a while since I posted anything. I do have several partly written, but I just haven’t had the motivation to finish them. So I thought I’d just put up a quick one today.
I bought this aluminum plate with a thin layer of green resin on the surface, which was claimed to contain “12000 grit diamond,” from AliExpress. I did some testing with it on my S110V Spyderco Para Military 2 and was surprised and disappointed to find that the hone wasn’t cutting the vanadium carbides in the way I would expect.
To investigate, I sawed off a small piece of the hone for analysis. A cross section through the resin layer shows that there is plenty of abrasive, although they are too large to call “12k grit.” Also, these are some very unusual shapes for diamond particles…
Next, I did elemental mapping on that surface, to see what the various materials are.
There are three distinct materials in the cross section. The sharp-edge particles are revealed to be silicon carbide. The dark region between them shows carbon and oxygen, as expected for polymer resin. The small, bright particles are chromium oxide, explaining the green colour of the resin. I don’t see any diamonds.
scienceofsharp 
21 responses to “A Disappointing Purchase”
is it a DMD?
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That’s the problem. Is it a genuine DMD, or did I get a counterfeit knock-off?
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there shld be some lettering on one of the sides
I have an extra piece and will ship to you a piece that I bought from DMD direct. do give yr address
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I think you mean like this:
As with all of my posts, there are more images and analysis than I discuss, as I am cautious to confirm the results I present. In fact, I purchased 3 DMD diamond resin hones from two different AliExpress stores nearly a year apart. All three are composed of silicon carbide with little or no diamond.
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In Japan, there are several such kind of sintered diamond sharpening stones and which costs more than USD150 any one.
I searched and found a sharpeningstone with such print. It was cheap, seemed to be made in China, and I couldn’t figure out what manufacturer made it.
There are many fake products in the world.
I think investigating for such products is a waste of time and effort.
I hope you will investigate about the grindstones that are highly regarded by carpenters.
https://www.naniwa-kenma.co.jp/sharpening_stone/diamond/
But unfortunately these products are not found in the lineup for the market in EU/USA/CANADA/AUSTRALIA
https://www.naniwa-abrasive.com/product/sharpening_stone/index1.html
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Wow, so cool to be able to verify these things. Hope you are doing well Todd!
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China?
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I’d act surprised, but… Well, you know…
Sorry that happened to you Todd. I hope it was cheap at least. Too bad you can’t return it at high velocity through their car window. =)
–Eric
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You should post a review on the purchase site with this link. It will go down in history as the most in depth review of all time.
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Hoping it was isolated incident or counterfeit prod. A real bummer in any case. Sorry u got burned. Many thanks for the heads up Todd.
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I purchased the 3k version too and it is also mostly silicon carbide; however, I did find a couple of diamonds in that one.
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No one expects the SEM-EDX!
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As consumers I believe we are being lied to on many fronts.
If a product states that it’s a diamond sharpener, I believe it is expected
That the majority of the product (excepting the base which it is applied to)
Is Diamond, not glue or a b c d e.
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There is a store on aliexpress which sells only DMD items. Maybe you can contact them.
aliexpress.com/store/5023099?
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Thanks for sharing, much appreciated.
There is a lot of information about a lot of things ‘out there’.
Finding good information is like finding 12000 grit diamond in a Chinese stone claiming it.
Thanks again
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Thanks for sharing, happy to see you got active again 🙂
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Hi,
Any “household” tests for diamond detection?
Also, FWIW, grey text on grey background is greeey 😉
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Not that I can think of, other than perhaps the performance on high vanadium carbide steel.
Interesting, I hadn’t noticed that the body text had switched to dark grey from black. I made the mistake of subscribing to wordpress.com for 3 years, so I am stuck with their awful editor for a bit longer.
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I hope it was cheap. I’ve bought several of the milled steel electroplate hones off of amazon or from china for around $20 with shipping. They’re pretty good. Everything else where production would be more expensive (sintered layer, etc), no thanks.
the 8×3 electroplate hones (usually listed 400/1000) often are listed in larger purchase groups for about $7 each, which explains why they’re often on amazon for $20-$25.
Aliexpress in general seems like a place where you expect to buy 10 things to get 7 good ones and write the others off. If there isn’t a big cost concession, it’s not worth the trouble given someone will buy a group of the same thing if it’s legit and sell on amazon for close to the same shipped price as aliexpress.
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Interesting, I also played with the thought of buying a cheap diamond resin stone, but you’ve convinced me not to.
Anyway, what I do not fully understand is:
a) the color of the ‘stone’, given that it looks mostly to be composed of SiC and cheap SiC being strongly absorbing, I’d expect something grey.
b) In the EDX mapping for C, the resin is much brighter than the SiC particles, which are essentially black with some noise, even though the SiC should be 1/3rd wt% C. The only abrasive, affordable, colorless, crystalline Si compound that contains no oxygen that I can come up with at the moment is Si3N4. Very untypical, but also significantly softer than VC, which could explain that. Did you observe any N in the EDX?
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Analysis shows the resin is about 85% carbon by volume (we don’t see hydrogen as it doesn’t produce x-rays) and the silicon carbide around 50%. However the incident electrons (primary beam) penetrates much further in the resin and creates more carbon k-alpha x-rays because we “see deeper” into the material there.
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