It is unclear why Rolex decided to produce porcelain dials at the end of the 1980s and soon stopped, though an educated guess would involved the difficulty of producing these items. The outcome is that today these pieces are outstandingly difficult to come by. Such scarcity, coupled with the ineffable aesthetic impact of the translucent dial, makes them the most fiercely hunted-down Zenith Daytona timepieces. It is truly once in a blue moon that a porcelain piece in such complete and correct condition as the present one comes to market.

Bearing a R9 serial number and “Floating Cosmograph” dial detailed analysis of the piece fully confirms its absolute correctness, as this breakdown demonstrates:

- Porcelain dials are found in the R serial range, then perfectly correct for this R9 example
- Case with serial between R9 and L24 should bear movements with number between 10’000 and 15’000. The present R99 example bears movement no. 13’651
- The fully brushed bracelet (78360) is correct - a version with polished central links (78390) will be introduced in 1991

When analyzing the guarantee, one can notice that:
- It correctly reads “Rolex Watch U.S.A., INC.” instead of the French wording
- The code R16520A50B7836 fully matches the watch. The first part being obviously the reference, the A50 indicates the white dial (A30 would indicate a black dial), and B7836 denotes the 78360 bracelet
- The stamp W RCTC to the front indicates the USA import month and year, decoded: June, 1989 - also perfectly matching what expected for this watch