Best way to install Fireplace gl doors on uneven brick?

We have a beautiful fireplace with uneven brick. However, the draft from the chimney is brutal and we're looking to install gl doors to cover the front of the opening. The galss doors we've bought stay in place fine, but have a gap between the frame and the stones. We will try to place the fire retardent insulation between them to fill the gap, but what can we use to cover that up so it isn't unsightly? Is there any other way of doing this?? Thanks in advance for your help.