Vintage golden IWC, 1940s-50s?

I have a vintage golden wristwatch made by IWC. It's at least 50 years old
sure, but based on my amateur research (lettering of digits etc.) it's most
probably made around late 1940s-mid 1950s. Mechanical, in working condition.
Definitely golden (checked at jeweller). Case is around 36-37 mm.

Would welcome more knowledge about this piece, as well as (at least
approximate) pricing. I've found same one on eBay, but it looks less used +
has different (more expensive?) band.

Guess this model might appear here in the past, so any links to other threads
are welcome. Sorry I'm starting a new one, but there's no viewing of threads
by image available, and titles are usually vague...

Hi Maritimus,

You have a very nice IWC Cal 89 wristwatch and I think the Ref number is R587
in 18K gold. Your 1950s estimate is accurate, but to know more, we will need
to see the movement number and the case number stamped inside the caseback

Thanks! Any idea (at least approximately) how many of these could be made?
Both in general (I noticed same design appearing more frequently with white
"face"), and this "yellow" variant?

Cal 89 was in production for a long time and very many variations were
produced.