Ref. 3970 The Ref. 3970 is now truly considered a classic by collectors, following in the footsteps of predecessors Ref. 1518, Ref. 2499, and Ref. 2499/100. They have become virtually unattainable to all but the wealthiest and most patient individuals. Hopefully, this note will shed some light on the different variations of the Ref. 3970 and help to better define its value, while clearing up misconceptions. Series: One can distinguish three series in the production of Ref. 3970. We define a ?series? by the variation in case designs or features, whereas we designate dial variations as being ?first generation?, ?second generation?, and so on. As a general rule, the Ref. 3970 was produced in 18K white, rose, yellow gold, and platinum, with platinum being the rarest variation, therefore always the most sought after. The first series of Ref. 3970 featured the 36mm. case with a snap-on case back. This particular model should be considered extremely rare, since it was made in fewer than 100 examples from 1986. The second series of Ref. 3970 also featured the 36mm. case, but with a solid screwed back. After the second series, Patek Philippe introduced the Ref. 3971, similar in design to the 3970 but with a sapphire crystal display screwed back. The company also received many special order requests to make the 3970 with an additional sapphire crystal display screwed back. The third series is known as Ref. 3970E (E stands for étanche, which means waterproof) and was housed in the same 36 mm. case. Because of numerous special order requests, Patek Philippe took the opportunity to supply the 3970E with both a solid gold screwed back and a sapphire crystal display screw-back. This is probably the most common of the three series. The earliest examples of the first series of Ref. 3970/2 with 36 mm. case featured a gold bracelet fixed to the traditional case; subsequently an integrated bracelet was used. A small number of early Ref. 3970/2 watches were sold with a solid snap back. Such watches should be considered exceptionally rare. The remainder of Ref. 3970/2 will be encountered with the more common screwed back. Finally, in the first and second series, the watches were generally sold with tang buckles, whereas in the third series (Ref. 3970E), after 1997, a deployant buckle was added. Dials: when Ref. 3970 was first introduced, Patek Philippe would occasionally accommodate a special customer?s request to order a custom dial. This often took place after the sale was concluded and resulted in some interesting and extremely rare case/dial combinations. As time went on, it became increasingly rare that the company accommodated requests for special dials. Consequently, any interesting or unusual dial variation can add tremendously to the value of the watch. The Dials: Let us now examine the two generations of standard dials: The first generation dial of these references was offered in twotone silver (very subtle) with baton markers. Generally speaking, the printing will be lighter on earlier dials, and the numbers on the date wheel will feature a serif font. The dials may be variously described as satiné silver or opaline silver. The second generation dial is silver (not two-tone as in the first generation) and features the same baton markers, but the font used on the dial will be slightly different, and the date wheel will be without serif. The third generation dial is silver, but with darker printing and triangular markers. The platinum and 18K white gold Ref. 3970s were also available with a black dial, and/or has diamond markers or white gold/platinum indices (the latter being much rarer). There are a very small number of ref. 3970?s in 18K yellow gold with silver diamond dials; such watches are extremely rare. Patek is also known to have produced diamond dials in both salmon and white. Again, Ref. 3970 with custom dials such as the ones described is exceptionally rare. Hands: during production, hands of the watch changed slightly. The earlier models (first generation) had leaf hands, whereas later models (second generation) had baton hands. It is not known when this change took place. One extremely rare variation on the Ref. 3970 has been seen with luminous dauphine hands. Movements: Ref. 3970 was fitted with Cal. 27-70 throughout its entire production. Although there are no variations in the caliber itself, the number system did change during the mid 1990s, when it went from a six-digit serial number beginning with 875 to a seven digit serial number beginning with 304. Ref. 3970 was replaced by Ref. 5970 in the Patek Philippe catalogue in 2005.