Now I got your point.
But saying that the movement is adjusted to COSC specs without the correct tools is almost impossible
Here what the COSC site says and I quote
" The results provide a "photographic" image of the rate of a movement at a given moment and certify its intrinsic position.
Nonetheless, due to their severity, these tests are highly selective and only extremely high-quality movements can hope to pass them.
This is therefore an examination based on excellence, even if the behaviour of the movements that are granted certification is still directly dependent on the wearers themselves.
To earn chronometer certification, a movement must not only be made from the highest-quality components, but also the object of special care on the part of the finest watchmakers and timers during assembly."
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