You see how its white in the picture, and not silver? That means its ceramic (aluminum oxide).
gerbergear itself says its ceramic.




Its not really related to price,
electroplated diamonds will get dislodged with high pressure
the surface area on those crock sticks is very small, the pressure is going to be very high, you need the lightest force possible to sharpen with, as in under 100 grams

The rods on mine are definitely diamond. It stated so on the package, too. Like this:
http://www.midwayusa.com/product/414633/...-fine-grit-rods
http://nicnac.net/contents/en-us/p1497_G..._22-107815.html



Heavy pressure is definitely a problem. That said, I have a couple of heavily used DMT diamond stones, still perform "as new". The diamond side on my DC4 has lasted many years of regular use too, even though it's now showing wear.

I also bought several sets of cheap diamond files and no-name diamond stones and sharpening cards. With only one or two minor exceptions, all lost their "bite" within minutes of first remotely serious use. YMMV.

I don't doubt they exist and I believe you own some, but we were talking about what haertig owns/linked



I don't doubt your experience.

My cheap diamonds are from harbor freight, 4 plate turnbox, they can be bought from $6 to $20,
I've damaged mine a little but they still have years of life left.
They definitely last more than minutes.

There are actually fake diamond stones/plates/cards made from diamond sandpaper (plastic) glued to a backing, those could be damaged easily going edge leading.