It’s not a special watch. It’s a Series 0 with $16k of gold.
We don’t even know if anyone ever bought a single one (as opposed to being given one by Apple/an Apple exec).
In 2015, gold was approximately $1250 per oz.
Perhaps someone who has a gold Rolex can correct me, but it seems unlikely that there is more than 3/4 lb (362 grams) of gold in it, even counting the band. That would probably be very tiring to wear.