Should be solid gold according to that hallmark. Just soak it in soapy water and rinse it and you should be good to go.
I'm hoping this is advice for the bracelet only, not dunking the watch too which will not take kindly to the wetting!
It'd be a crying shame to soak that dial.
Update: Just took the watch in to my local repairman to get serviced, but I was able to take a picture of the inside back of the case, if this can help anyone figure out which model it is.
Thank you.