Originally Posted by
Koyote
If we're supposed to help you determine whether the stem is appropriate for a 31.8mm bar, you're showing us the wrong view. Do the concave stem surfaces mate perfectly (=flush) with the handlebar? Also, when you screwed in the bolts, did they go a ways into the opposing threads? In other words, did they get sufficient purchase? If the answers to these Qs are both "yes," you're probably fine.
The surface is quite flush. I realized that and took it for a test ride. It felt very stable. I also found some pictures of the stem online and it seems to typically have this gap. Thank you for the help!