In Schaffhausen, the employees had been making bets as to how many of the new Da Vinci watches would be sold. In view of the sales figures for watches with perpetual calendars published by other companies, some thought perhaps ten to 15 while the more optimistically minded figured a maximum of 30. So when Günter Blümlein returned to Schaffhausen with orders for over 100 watches, everyone was amazed. Their amazement necessarily gave way to serious planning. IWC had to place an order for much more gold for the cases than originally agreed with the suppliers. To manufacture the blanks for the gold case of the Da Vinci, IWC used a process that had already proved its worth in the production of titanium cases.
As a way of preventing the cavities that occur in standard casting, the company adopted a technology used in the aviation industry for the production of aluminium cast parts. The process in question, known as hot isostatic pressing/postcompaction (HIP), is also suitable for use with other metals. Until the 1980s, it was standard practice in the watch industry to mill cases from a block of gold. The HIP process now made it possible to cast high-quality, cavity-free gold while significantly reducing the time required for machining the blanks in Schaffhausen. The Da Vinci set up another innovative milestone in case production a year later in 1986. This was the world's first watch case made of yttrium-stabilized zirconium oxide ceramic. It created a sensation when it was presented in the shape of Ref. 3755 to the world press.
In retrospect, one thing is clear. In 1985, as inventor and design engineer of IWC's perpetual calendar, Kurt Klaus wrote watchmaking history. In the Da Vinci Ref. 3750, the mechanical watch displayed all its beauty and complexity. Like the phoenix rising from the ashes, a universal symbol of immortality and renewal, the Da Vinci appeared at a time when the mechanical watch had virtually sunk into oblivion. For both IWC and the entire watch industry, 11 April 1985 marked the start of a genuinely complicated era.