Cheng adds that he had noticed that Midas appeared on the dial of more white-gold and bi-metal versions of the ref. 3580 than on yellow-gold examples. “The decision by Rolex to use up the remaining Midas dials from the original 9630 production run is another example of something the brand would never do now,” he says.
Over the years, several later-numbered ref. 3580s, and indeed even later references, have come up with Midas dials. “The most plausible explanation for this is that over the years, a large proportion of King Midas watches were smelted down for gold,” says Knospe. “That left a surplus of calibres and dials, some of which were fitted to watches produced after the Midas name disappeared from the dial.”
Another relatively small update was the calibre 651 – a minor iteration of the calibre 650. Over the course of the ref. 3580’s short four-year production run, Rolex created fewer than 500 pieces; most of them were in yellow gold, with a much smaller number made from white gold.
While the 1970s had begun with gold prices at $35 per ounce, by the end of the decade prices had risen by more than 500%, standing at $850 per ounce. This started reflecting in the ref. 4315, which was first revealed in 1977. Produced for just two years, it is marked apart by its thinner bracelet which did away with the double deployant for a single fold clasp. Another key difference is that the bracelet, screwed on to the case, can be taken off. While the proportions of the case were unchanged, it wears very differently due to the thinness of the bracelet and a reduced 125g weight. On the inside, the calibre 651 continues.
Most references from the 1980s transitioned from the calibre 651 to the calibre 1600, and then to the calibre 1601, both produced in-house by Rolex. They are similar in specification to the 651.