Glass fireplace doors can add an elegant framing effect to your home fire without obstructing your view of the blaze. They come in a variety of standard sizes that will fit most pre-installed masonry fireplaces or prefabricated designs. For an odd-sized fireplace, or simply for an added level of precision, you can have glass doors custom built to fit snugly.
Whether choosing a custom or stock design, you do need to ensure that your glass doors fit snugly. When the fireplace is not in use, poorly fit glass doors can increase your heating and cooling bills by creating a disadvantageous air exchange with the outside world. Pre-made fireplace doors will come with an overlapping flange to make sure that the seal is secure. Custom made designs won't need the flange since they can be precision engineered to exactly the right fit. Custom built glass doors can cost over $2,000, but many homeowners feel the effect is worth it.
You'll want to get glass doors that open and close easily without requiring a lot of force. Strong door hinges will help make this a reality. Doors that attach with a spring latch system can provide a more effective seal. A mesh curtain that won't curl or lose shape is also a plus.
The glass itself can be simply clear for a bright effect, giving you a full view of the fire. If you prefer a more muted look, consider tinted glass in translucent smoke, bronze, or even black. This can add $65 or so to the cost. For an extra touch of elegance (and another $75), the glass can be beveled. Or for a simple, rustic look, you don't need any glass at all. Instead, the panels can be constructed of rigid mesh that swings aside on hinges just like the glass doors. If you go this route, you'll want to make sure the fireplace damper creates an airtight seal or that the gas fireplace vents seal tightly when not in use. You won't have any doors as a backup defense against losing heat to the outside world.
The simplest door design is a rectangle with trim along the top and bottom and handles in the same color as the trim along the top. This maximizes the viewing area for the fire with an understated frame while still providing a means to get the door opened and closed. Above and below the trim, you can have a simple braid or grill design, perhaps as part of a venting system that can be opened and closed to minutely control the air flow.
If your fireplace has a standard arch design, pre-made glass doors exist to fit it. But maybe you've got a rectangular opening and would still like an arch design. Glass doors can accommodate this as well by placing an arch within the rectangle. This won't really cut off any of the viewing area for the fire itself. You'll only be blocking off the upper corners of the fireplace where nothing much happens anyway.
Glass fireplace doors can come with a variety of different trim around the edges. Satin, antique, or polished brass, bronze, copper, nickel, or pewter are popular options. Chrome, mahogany, and iron each make their own statement. Bright or flat black can have an understated elegance. And any shade of gray or brown that you can imagine is also a possibility.