Jaeger Lecoultre Master Ultra Thin Perpetual Calendar 39 mm. The three original versions.
In one picture: Steel, white gold and rose gold. ( Steel on the right, white gold on the left ).
These first three received a warm welcome, in 2013, and rightly so.
Still, my favorite remains the steel black which came two years after.
Over the white gold grey ( 2017 )
Or the white gold guilloché blue enamel ( 2019 ).