ROLEX: THE KEW “A”

In the 50s Rolex undertook the challenge of submitting its watches to the Royal Observatory at Kew for chronometer testing. Almost all of the tested watches passed and received the coveted Kew “A” certificates and the distinction of “especially good results” meaning that they produced rating in the top 20% of the accuracy needed to obtain a Kew “A” certificate. It was confirmed that the daily variation was less than half a second.

After obtaining their certificates, the movements were returned to Switzerland and cased prior to sale. Some of them required multiple testing so it was quite common for watches with sequential movement numbers to have case numbers all over the place

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