In my corner of the world (Central FL), these windows are called butt-glass windows. The glass panes are "butted" against each other and sealed with silicone. We love the one we have in back at the breakfast nook. It is under a porch roof. It went through 3 hurricanes in 2004 without a leak and looks great! Good luck in your search.

A quick google search on "butt glass" turns up lots of hits, some sites with pictures of beautiful corner windows. I love them.

I have no experience with them, but the google search turns up glass companies, not window/building supply companies.

I don't think you "buy" them, I think you have a specialty glass company fabricate and install them onsite.

Perhaps beachlilly can answer whether she bought the windows ready-made, or had them custom fabricated and installed onsite.

Also, can this be done cleanly using double-paned glass (insulated), or are they fabricated from a single pane of thicker glass?

I had a couple of those types of windows in my previous house. The main drawback is what chapnc picked up on - they're single-pane and thus have terrible insulating properties. It might be possible that there are dual-pane versions out there, but I've never seen any and am not sure how it would be technically feasible.

If you're in a mild climate like FL then they'd be great. In severe climates I'd be a bit leery of them. Personally after my experience with them in my previous home I wouldn't want them again.

Butt glazing refers to glass that does not have a structural support at the vertical edges and the narrow joint between panes is filled with clear sealant to keep out the weather. This kind of glazing system usually uses thick single-pane laminated or tempered glass for strength and for a narrow sightline since that is the point of butt glazing.

Butt glazing of double-pane glass exposes to view the interior seal in each pane of glass. When the seal is exposed to the weather in a corner joint a small mullion (tube or angle) is usually used and sealant is added between the mullion and the glass. This is technically "structural glazing" although the mullion may not be offering much support so it could be considered a form of butt glazing.

Most residential window manufacturers have made a glass corner window at one time but I don't know of any that still make them except as a custom order. The Marvin Custom Shop will make anything.

Several years back I remember seeing a advertisement in an architecture periodical showing insulated glass windows that had frame-less corners. The corners were rounded around the corner in one piece rather than mitered glass of two pieces. This achieved the same effect but allowed for two panes of insulated glass. I do not remember the manufacturer but have been trying to locate them. if anyone has seen this let me know!

Most of the companies that offered them chose to stop due to the inability to maintain the seal on the unit and caused many fogging issues.

I know that fleetwood of CA has one. I recently saw a sample in my window and door guy's shop.

Is this what you're looking for?
"A bead of structural silicone joins energy efficient, double-glazed, mitred glass panes cleanly at the corners. With no corner mullion, seamless views are achieved, highlighting spectacular views at every corner."

Here is a link that might be useful: Unisonn corner windows

A true seamless double pane glass corner requires the each glass panel to be bent. Marvin used to do this but after 1999 only does it with single glazing.

Butting/mitering double pane glass at a corner requires each pane to be sealed to the other pane and then the two panels are brought together and sealed with structural silicone and sometimes with a narrow metal angle or tube the same width as the glass thickness. IMHO such a joint looks worse than one with a thin mullion that hides internal glass seals. Marvin provides such a window design.

From what I understand no one really offers this any longer as the seal was about impossible to keep intact. Also bryce you did notice this post was 3 1/2 years old right?