Hi Darren. I'm in Berlin atm, so away from my picture library so I can't link a picture until I get back.

Cal 15 blue dials fading to violet in sunlight affected the Monacos as well as the Carreras (better make sure I spell it correctly, even on this netbook's keyboard!) and is something that has been discussed a few times on the forum. Shaun posted two 1533s side by side before to show the comparison, one recognisably its original blue, the other distinctly violet. I found that post with a search but the picture link is broken now :( I might still have the photo on a HDD somewhere though, I'll look when I get home.

The dial finish on Cal 15s is quite distinct from the Cal 11/12s; though some 1153s do have dial problems of their own, it's not usually a fade to violet. The first 1153s have what Heuer referred to as a charcoal grey dial, which usually remains fairly intact, just gaining an even patina - I think I've only seen one beginning to suffer the serious paint loss that ends up with the brassing so beautifully shown by Jeff's Chronomatic Monaco. The next dial was a dark blue and again this seems pretty resistant to change - if anything, they go slightly lighter blue with UV exposure but the change is relatively marginal. The "yachting" Carreras have a different finish all of their own, much more metallic than a regular 1153, which seems to be a bit more temperamental than those dials; the most common problem I've seen with those though is bubbling of the paint on the (black) registers rather than with the blue of the dial. Finally, the 110.253 had a different dial again - in fact, it used the same dial as the blue barrel-cased Carrera; in extremis, those can lose the CdG detailing and can even end up with a similar lapis lazuli effect to Nic's watch.

Now, I've identified four distinct dials for 1153s there but it's important to note that Heuer and Singer (I think all 4 are Singer dials off the top of my head, would need to check dial reverses to be sure) were playing around with the finishes in each of those four "families", if you like, to try and improve resistance to change under UV, moisture, salinity etc. Some of them can indeed fade to violet like a 1553 dial, but they don't do it as often or as readily as the 1553s do. The 1553s do it so nicely and so evenly that it's well worth picking up a violet dialled example if you see one - rather than detracting from the watch, in my eyes it adds to it. Unfortunately, my 1553 is resolutely and steadfastly blue!

All of this is about identifying trends, of course. What happens to an individual watch is down to its unique levels of exposure to sun, darkness, moisture etc etc, so each one can be happy it's its own special little snowflake but that doesn't stop us formulating an idea of what the "usual" changes, if any, to the dials of a specific model are. I find this a really interesting area of the whole collecting malarkey, but probably not everyone does so I'll stop there!!