Your opinions about KOETSU URUSHI BLUE or VERMILLION

I have never heard the Vermillion, but have owned the Sky Blue.
The Sky Blue had good dynamics and real bass "slam", but was a bit too euphonic for my taste, mounted in an SME V. 

I’ve got a Vermillion which I use in an FR66s arm; it’s a really nice cartridge, very holographic, great dynamics, excellent tracking and minimal edge or nastiness to the sound.
Compared to my other Koetsu, a Jade with diamond cantilever, I’d say the Jade has a more “authoritative” feel. With the Jade you get the same as the Vermillion in terms of all the things listed above, but there’s something more explosive and solid about it (in a good way :)). One thing that is palpable is the lower frequencies with the Jade, the bass is really good, the best of all of my cartridges in that regards. That’s not at the expense of midrange or higher frequencies , just something that really stands out.

tkr, it is that euphoric quality that some of us love about the Koetsu's. You would have to add a lot of weight to the SME V to get the bass right.
I use my Koetsu for string quartets and the like not for R+R and rarely for Jazz. The other cartridges I use are more neutral and to my ear more accurate not to mention better trackers (more accurate is not equal to better sounding.) 
mulveling, I certainly can not argue with your opinion. The FR's are certainly heavier arms. I would never use a Koetsu in a uni pivot arm. Actually, I would never use anything in a uni pivot arm so I guess that is not saying much. 

tkr, it is that euphoric quality that some of us love about the Koetsu's. You would have to add a lot of weight to the SME V to get the bass right.
I use my Koetsu for string quartets and the like not for R+R and rarely for Jazz. The other cartridges I use are more neutral and to my ear more accurate not to mention better trackers (more accurate is not equal to better sounding.)

I think you misunderstood my post. Actually, I had no problems with the bass of the Sky Blue at all. As I wrote, the Sky Blue had a great bass "slam" and dynamics. 
My problem was that it sounded a bit too warm and cuddly or, if you want, euphonic.
My solution was to upgrade to a Koetsu Coralstone, which is a totally different beast. 

The Vermilion does *not* have silver-plated copper wire.

"This is the only Urushi cartridge that uses a double-coil winding of silver-and-copper – not silver-plated copper – and the coils here are made with fewer turns. Thus it has the lowest output of any Koetsu at 0.2mV, and half that of any other Urushi."

https://www.hifinews.com/content/koetsu-urushi-vermillion-cartridge

I have heard great things about it and it's the one I would buy, shopping at that level for a Koetsu. Hopefully next year.