Bo-hi is what I mean. Me was takin English.
The cross section of a "raised ridge line" looks kinda like a diamond shape.
got it now?
Only Nihonto I've seen with a diamond cross-section throughout are Moroha-zukuri, which are double-edged throughout their length. They are rare as Tanto, rarer still as Wakizashi, and AFAIK nonexistent as Daito.
Maybe you're thinking of Kissaki-moroha-zukuri? Double edged for only a portion of the blade, maybe 1/3 the way back from the tip. Cold Steel sells a version of this.
I suppose, if one loosely defines a diamond cross-section, one could consider the U-no-kubi-zukuri under this category. This involves a beveled, but not sharpened, spine, which widens to full thickness at the tip and for a bit towards the Habaki.
I love all of these blade shapes. Katana in general have come to bore me, since almost all one sees is boring black Ito and black Saya on Shinogi-zukuri. It's the offbeat stuff I really like.
That said, I have a jet-black Chisagatana from Cold Steel. Not an overly interesting geometry, but it's a hellish cutter. Plus I modified it, so it's a litttttttle bit different than the norm (I think my picture thread is still on the main sword-discussion page).