Koestu original Onyx Sig pre-platinum cart vs. later/current platinum Sig comparisons

I have had good success with a Rosewood Signature Platinum on a FR-64S.  The pre I use is a Pass XP-27 which I preferred to a SUT/MM input combo.  Not sure about how one dates a stone body Koetsu.  Did you have a chance to examine the stylus with a microscope?

@edgewear

By now I’ve seen pics of several slightly different pre-Platinum Onyx short bodies; it’s almost impossible to say exactly what you have, unless you get in direct contact with Koetsu. Still so much mystery with Koetsu!

I don’t personally know of any Platinum Koetsu that doesn’t have a leading "P" in its serial number, but that doesn’t mean it can’t exist. There could be pre-Platinum Koetsus that were later rebuilt with Platinum magnets (with original top plate retained).

You might join the "Koetsu Users" Facebook group, which has some interesting vintage Koetsus posted & discussed by members. These groups have the advantage of easy image inlining.

In a revision of my previous comment on this thread, I would now estimate my non-platinum Onyx at between 0.4 and 0.5mV output. Not fully double the Platinum model’s 0.3mV, but still quite noticeably higher. I would guess its magnet is most likely samarium-cobalt or permendur (i.e. like the Black, Rosewood, and Urushi models). The fabled long-bodies should use alnico - very large alnico magnets were necessitated by the (relatively) weak magnetic material, which required the long bodies to house it!

As to sonic matching - I absolutely prefer all my Koetsus with EAR SUT (or Koetsu SUT, or Quadratic MC-1 SUT) over any active MC stage, including that of my ARC Reference 3SE. FR64S and 64fx arms here. But then, every system is different! 

Not sure about how one dates a stone body Koetsu.

Carbon dating?

Platinum magnets are like green eggs and ham.

I do not like green eggs and ham.

I have dated numerous Koetsu's over the years, and the allure has waned with the passing of the old master and the advent of platinum magnets.

I experiment with swapping a lot of gear - depending on partnering gear, the non-Platinum magnets (Onyx in my case) work better in some cases, and Platinum works better in others. The non-Platinum magnets have more output to work with. They're also a bit more brash and dynamic / punchy sounding. The Platinum magnets are smoother and more refined sounding. But OP need not stress over which magnet his Onyx has - just listen and enjoy! The Platinums cost more but are not necessarily better. 

Blue Lace Platinum combines the smooth lushness of Platinum magnets with better dynamics and detail compared to other stones or RSP. It's the best. I also like Onyx Platinum, but it lags a little behind the Blue Lace. The warmer / softer sounding stones like Jade and Coralstone can be just too over-smoothed for many systems.