Koetsu cartridges. They must be something special.

One observation for which I don't have an answer- the Jade sounds different than the Tiger Eye on the same system. From what I gather the innards of both cartridges are the same. The difference in the hardness of the stone is recognized, generally (you can look it up under the Moh Scale for each). I don't know how much that contributes-- neither stone absorbs resonance in the same way that something like wood would; and there was the myth that the better motor assemblies were reserved for the upper tier Koetsu but I think its just that, a myth. 

I will probably try Ana Mighty in France when I'm due for a retip; I gather they had some history with Koetsu back in the day. Those Medialux articles posted upstream are a pretty good introduction to the product line; sadly, the company is no more, though I understand why the family opted not to "sell the brand" to a 3rd party-- it would not have been the same. 

It might've been even better, and that's not what they wanted.

I like the sound of the stone-body Koetsus.  Most of my friends who own or are familiar with the lineup prefer the Rosewood Signature Platinum.  It is a matter of personal preference.  Regardless of the science, the cartridges sound a little different.  But, I suspect, a choices made between the types of stone-body cartridges is primarily based on appearance.  I have seen most of the types, and my favorite look is that of the Blue Lace.

I've had a Koetsu Rosewood Signature Platinum for almost fifteen years now. It has been a wondererful treat.

By the way, my local dealer has sent several of his own and customer Koetsu cartridges for repair/re-tipping to Andy Kim in California.  He is very pleased with what he got back.  It appears that Koetsu will live on well into the future thanks to services like this one.  I think it took Andy Kim a couple of week to do the repairs on an Allaerte my dealer sent to him, and the "delay" in receiving back the cartridge was because new parts had to be ordered from Allaerte.