I think you mean 23j which is the supposed jewel count for the high beat basic movements. I've had a few through my hands recently and all they are is a slightly upgraded 21j movement. IE a 4813. Which have been around for a long time but supply dried up in Rolex watches because they weren't being supplied with the higher pinions to make room for the date wheel overlay.
They are still based on the 21j (DG2813 etc.) movements from what I've seen and will not take ETA based hand sizes.
Would love to see some pics of this 'semi-clone'.
No, I did mean to type 25j, because that's how the dealers selling this movement have designated it.
I don't know if you have read all the threads about this new movement lately, but there has been a good deal of discussion (and contention) about what it actually is. Josh describes it on his site as a "new breed 25j
Movement", and it looks superficially like either an eta clone clone or a dg3804, depending on who you ask. It beats at 28.8k, but is not (or so I understand) a 4813.
I'm not an expert on movements, but even among those who claim to be there has been no consensus about this movement's origin or design. I read that it has eta-sized hands posts, but I can't say for sure whether this is the case.
Here's the pic from Josh's website:
People that have purchased it describe it as feeling much more robust than the dg2/4813 movements, but who knows?