Diamonds are just dirt cheap. You can buy a set of ten diamond needle files for $8 on Amazon, or less than $2 in wholesale quantities. I have hundreds of grams of diamond in my workshop in the form of lapping compound; if you're so inclined, you could buy half a kilo of loose diamonds for a couple of hundred bucks.
A wide range of very ordinary cutting tools are now tipped with big chunks of polycrystalline diamond - cutting tools for machining aluminium, inserts for rock drills, saw blades for cutting fibre cement boards. Even woodworkers are starting to use diamond saw blades and router bits, because the improved wear life over tungsten carbide gives a rapid return on investment.
I bought that exact set of red-dipped-handled cheapo rifflers 19 years ago (2005, I remember I was still at school, and I think they came from Maplins, possibly Rapid). They were cheap then too, probably about the same numerical price, perhaps £10 with the Maplins tax, and AliExpress shipping was just a gleam in Jack Ma's eye. Industrial-grade diamond dust has been pretty cheap for a long time.
Same. I even have that set from Amazon and am happy with it. It's not the best, but there's always uses for cheap files.
Also this is the first time I've tried to go to ali from my phone and holy hell are they aggressive in trying to get you to use the app. And express links require login? WTF. It crashed my browser
A wide range of very ordinary cutting tools are now tipped with big chunks of polycrystalline diamond - cutting tools for machining aluminium, inserts for rock drills, saw blades for cutting fibre cement boards. Even woodworkers are starting to use diamond saw blades and router bits, because the improved wear life over tungsten carbide gives a rapid return on investment.
https://www.amazon.com/Yakamoz-10-Piece-Diamond-Jewelers-Pre...
https://www.alibaba.com/product-detail/140mm-160mm-180mm-Dia...
https://www.aliexpress.com/item/32719545477.html
https://union-diamond.en.alibaba.com/index.html
https://www.aliexpress.com/item/1005003335883020.html