This weekend was an eventful one as I have traded my Rolex handwind Datejust tropical for a smooth bezel 1600 which is quite rare as it has a special dial too. Datejust Ref 1601 comes in fluted bezel or 1603 crenelated bezel while the 1600 is quite rare as it looks ordinary those days with the smooth bezel.
In addition, it has a dial which have fonts "O T SWISS T O" towards the bottom area, denotes that the markers are made of white or yellow gold. The word sigma dial is used because the letter O's in the O T SWISS T O appear to look like the the 18th letter in the Greek alphabet σ or the Mathematic symbol for sigma.
Please read: https://shop.hodinkee.com/products/1969-rolex-datejust-reference-1600?variant=19799007428
In addition to the trade, I have also managed to find a nice Rado NCC101 in Blue Lapis dial. It is a massive watch and the lapis dial immediately captured one's attention. I didn't know that this model of NCC 101 is in demand until I serf the net forum.