ON IT.
*
Actually I did just go out to Drew's to confirm my theory, and yes, you aren't quite deep enough for diamonds yet. I think they start at 15? Maybe 12. Either way you're a few levels too high.
I don't know that I've ever been out that way in the daytime. Neat place.
* Speaking of... did I never put hangars up in that short strip next to the new portal? Sheesh. First time I noticed.