Thank you all !
The owners are very lucky! Can I ask where in the world are they going?
One will go to Japan. The other one to the USA, or to Singapore, not sure yet.
it was a good surprise for me in the video that you are using the phosphorescent sphere for the balancing method, very good!
Yes, the phosphorescent ball is not only for aesthetics.
Just for curiosity, about the incredible sensitivity of tops, as for unbalance:
the unbalance wobble you saw in the video was obtained by screwing out one of the grub screws by three turns, and the top was perfectly balanced before.
The thread pitch is 0.8 mm so with three turns the screw was shifted outwards by 2.4 mm.
The screw weighs 0.9 grams and the top weighs 282 grams.
So the center of mass was shifted by
2.4 : (282 : 0.9) = 0.008 mm
So, the center of mass being off centered by just only 8 thousandths of millimetre produced that evident wobble in the video.
With this kind of tops, the good balance is really a matter of thousandths of a millimetre !