Judging by your description it sounds like a 980.029 Pro Diver to me,nicknamed "black coral".
Like the one seen here on the far left?

I wouldn`t state an exact value,it depends highly on the condition and wear.Being a quartz,it`s probably not too attractive to other than Heuer collectors as well.
I`ve seen these go on the bay for as little as 30 $ (usually defective or very hard worn watchhead only),and for as much as 3-400 $ for a complete watch with little wear.

Sorry I can`t be of more help,if you ever want to sell it drop me a line though,I could be interested.

Cheers!
Marius

: I have a Heuer from the mid 80's I bought in the islands. It is
: Black and gold and I have been trying to figure out what model
: it is. It has a one way bezel with black and white face the face
: of the watch is black with a date.It has the Mercedes hour hand
: and is marked quartx 200 meters professional.Been setting in the
: drawer for years and has a lot of wear on the band but always
: was a great watch.
: Can someone provide me with a little info as to what to look under
: to find out about it's value?
: Thanks,
: John