It's a masonry fireplace - so definitely custom.
Looks like they may have used a Rumford firebox kit in it's creation:

http://www.rumford.com/components.html

First off, beautiful work by modern house architects - I love the way the surround is floating.

But I'm curious, too. Several elements - the gas logs, the frameless glass doors, the inside hearth being raised slightly off the floor and the metal chimney - lead me to believe this is a manufactured unit instead of a custom masonry fireplace (although @bepsf is absolutely right about the Rumford proportions).

Anyone from MHA that remembers?

Thanks for the responses. This is the first time I've used the question function. We're deconverting a two-flat into a single family home, and this site is coming in very handy.

This was created using pre manufactured firebtick inserts w/ a custom conc. Block clad with stained conc. For the exterior.
Also behind the free standing fireplace is a sandblasted window which creates natural light day glow in the daylight and we light at night from the exterior for a sim. Appearance at night
C.C.

Is this the exterior elevation? http://www.houzz.com/photos/81870/Main-Entry-Guest-Bedroom-modern-exterior-san-francisco

Do you remember who the firebox manufacturer is?