I am very, very lucky and ecstatic to have received a new Blue Lace w/ diamond cantilever. This extends my experience to a 6th Koetsu. It's still fresh out of the box, now with maybe 5 hours on it from initial testing after setup, and one long late-night listening session - not anywhere near burned in yet. But the experience it provides is so compelling, I felt like writing about it already. My girlfriend also noticed a striking difference in our long listening session; we swapped the Coralstone in-and-out to confirm (Ikeda headshells make it easy). In short, the Coralstone boron I've enjoyed for 2 years (still in the prime of its life thanks to careful use in a multi-cartridge rotation) has been handily dethroned. I'd rate the differences between stones (Onyx, Jade, Coralstone) as "subtle". The difference from Rosewood (RSP) to stone is "moderate", in the favor of stone (most notably in bass). The differences between magnet types alnico vs. platinum is significant, but not all differences favor one type vs the other. The differences between boron and diamond cantilevers seems to also be significant, except this time all in favor of the latter.
Sonic Impressions:
The verdict is clear - this is next level Koetsu sound, by a fair margin, over the Coralstone boron and all other Koetsus I've owned. There's no gray area here - this is the superior Koetsu of my dreams.
The tonal balance is not warm like the Coralstone boron. Nor is it bright - in fact I find it to be smoother and less grating up top on harsh recordings. The sound from top to bottom is crystalline in how pure and cleanly delineated even the most minute details are. There is absolutely no blurring or fuzzing of lines in any way perceptible to the human ear. This level of hyper-detail is normally what I associate with bad sounding, overly high-tech hifi - where the detail actually fights against the musical experience. That's not the case here - music actually flows BETTER than it does on the Coralstone boron; in fact it matches state-of-the-art open reel tape playback in this regard (which I consider to set the bar for world-class sound reproduction, despite my very limited experience enjoying this medium). The extra detail also gets you even more spatial information. The combined effect is that vocals - the strong point of every singe Koetsu every made - here sound like the performer has physically beamed right into your room. It's amazing. Bass impact and volume are about the same between Blue Lace DC and Coralstone boron, but the former is significantly cleaned up, while the latter is a bit bloomy/fuzzy by comparison. Like a lens that was slightly out of focus.
The diamond cantilever upgrade is not diminishing returns, unlike so many expensive pursuits in this hobby. If you've gone this far to purchase a Koetsu stone or RSP, I think it's imperative to stretch the extra bit for the DC (any of the Platinum models, including the Rosewood Platinum, can be upgraded with a DC). It's that much of a difference maker. I'll be doing everything in my power to keep a Koetsu diamond running until I die - I don't drive a fancy car, eat fine cuisine, or travel for exotic vacations; this is the only luxury I care for and pursue! This is now one of 5 "blow me away" moments in the lifetime of my audiophile hobby (two of which were headphones and don't count towards 2ch; the other to being first hearing a Tannoy dual-concentric and the other being my move from digital to vinyl), and this was the most impressive given it was performed over the incredible Coralstone boron.
System:
Tannoy Canterbury GR
Rogue Audio Apollo Dark tube monoblocks
Audio Research Reference 6 preamp
VAC Renaissance SE phono stage
EAR MC-3 SUT
Clearaudio Master Innovation table w/ Clearaudio ring clamp, Stillpoints Ultra SS and LPI
Critical Mass Systems Maxxum rack
Fidelity Research FR64S arm with Ikeda IT-VTA-06 base
Ikeda IS-2T headshell, Ortofon Japan L800S leads
Audioquest Niagara 7000 conditioner
Audioquest WEL Signature signal cabling
Audioquest Hurricane PC's
Below pic is from a few weeks ago, pictured with Coralstone boron. I also swapped out the old Fidelity Research B-60 for the Ikdea IT-VTA-06 base at the time I installed the Blue Lace. The new Ikeda base tightens up a lot better than the vintage B-60!