Ruby and Boron Carbide Oilstones: Good or junk?

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Papilio

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Sep 6, 2019
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What do you think about those (Chinese?) Ruby and Boron Carbide oilstones? Ruby is rated as 3.000 grit and Boron 800 (sometimes rated as 1.000). They come in different sizes. Both stones are described as being (very) hard, i.e. they seem to wear only slightly.

Sorry, I could not find a list with authorized vendors. I apologize myself if the linked shops are not permitted again.
Stones like this ones:
Ruby
link to non-supporting vendor removed by staff

As they are cheaper (same dimension, same grit?) as a Spyderco Bench Stone (medium, fine) or Arkansas Stone (Hard, Hard Black), I am curious if those stones are good or rather junk.
Thanks
 
Ruby is a very good abrasive, being a form of aluminum oxide with trace amounts chromium, and it's a tough and hard-wearing variety that comes at a premium price. I use ruby abrasive in my Bull Thistle series of stones. Boron carbide is generally used only for grinding wheel dressing, and is VERY hard bond as a result. Sintered ruby is very expensive, but as with pretty much all sintered stones is a multiple-lifetimes investment and as long as you don't break it it'll never realistically wear out (though you do need to dress the surface occasionally to expose fresh grit.) Sintered boron carbide exists, but is EXTREMELY expensive. Most people purchasing sintered ruby stones seem to use them for gravers and dental instruments. Most Chinese-made inexpensive boron carbide stones out there that you'll find probably have little, if any, actual boron carbide in them. I seem to remember an analysis that was done by someone in the straight razor world that reached that very conclusion, but could be remembering incorrectly.
 
there are different qualities of chinese rubies, so one needs to see the difference and not think that the one you got is the reference.
imho rubies are a must have in one's arsenal, cheap and or expensive. i use both.

love the color
 
As my Hard Black Arkansas works great, there is not a need to buy a 3.000 grit Ruby stone. Although it looks really nice, the colour is an eyecatcher. Good to know that there are different qualities because the look more or less the same and so is their description.
The Boron Carbide stone would be more interesting, but if it is a Boron Carbide stone without Boron Carbide...well, that does not sound like a good choice.
Dressing the surface to expose fresh grit is possible with SiC powder, wet-and-dry sandpaper, as far as I know. Would barkeepers friend work, too? Or is that just for cleaning? Let's say I use sandpaper. That is available in many different grits from extra coarse to ultra-fine. Doesn't the sandpaper's grit affect the surface finish, i.e. how coarse / fine the surface will be? What would be the right grit for a 3.000 grit stone?
 
Papilio said:
As my Hard Black Arkansas works great, there is not a need to buy a 3.000 grit Ruby stone. Although it looks really nice, the colour is an eyecatcher. Good to know that there are different qualities because the look more or less the same and so is their description.
The Boron Carbide stone would be more interesting, but if it is a Boron Carbide stone without Boron Carbide...well, that does not sound like a good choice.
Dressing the surface to expose fresh grit is possible with SiC powder, wet-and-dry sandpaper, as far as I know. Would barkeepers friend work, too? Or is that just for cleaning? Let's say I use sandpaper. That is available in many different grits from extra coarse to ultra-fine. Doesn't the sandpaper's grit affect the surface finish, i.e. how coarse / fine the surface will be? What would be the right grit for a 3.000 grit stone?
Click to expand...
Ruby will cut steel with chromium carbides commonly found in many tool steels and stainless steels while Arkansas stones use silicon dioxide (quartz) as the abrasive, which is too soft to properly cut those carbides, so generally you'll get better results out of ruby. Arkansas stones are best reserved for plain low-alloy carbon steels, though they work well for that. Boron carbide is the softest abrasive capable of abrading vanadium carbides, but for ultra-fine honing usually a diamond or CBN emulsion on a hard strop is the most economical route if you really need that high of a polish on a high-vanadium steel.
 
Alberta Ed said:
Diamonds are a knife nerd's best friend.;)
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Thanks, Marilyn...ups...Ed!😉
High quality diamond stones in different grits (like Atoma, DMT, EZE-LAP) would be nice to have. Wouldn't they be so expensive.

I know that Arkansas stones are just a 7 (?) on the Mohs scale of mineral hardness and that it is difficult to sharpen hard steels with Arkansas stones. Mostly I use softer steels. I have a knife made of 440C, but I sharpen that knife on ceramic pocket stones. Ruby is interesting. Makes me think...
 
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