What a diamond vent is
A diamond gable vent is a square turned 45 degrees, so a point faces up. The slats stay level. The outline is the accent. It reads as a deliberate ornament, which is why it suits a smaller gable better than a huge one.
It is molded high-density polyurethane, factory-primed white, and ready for paint. It does not rot, and it cuts and fastens much like wood trim.
Where it looks right
Use it on a smaller gable, a dormer, or a garage, where one bold shape can carry the wall. A diamond in the middle of a very large triangle can look lost unless you size it up. It also suits a house that already uses diamond panes or a diagonal pattern in the siding or the porch rail.
The top and bottom points should sit on the center line of the gable. If the side points are not level with each other, the vent is rotated and will look crooked even if the slats are level.
Open or closed
open diamond gable vents pass air. closed diamond gable vents are the same diamond with a solid back. On a small decorative dormer, closed is often enough. On a garage attic that actually needs air, use the open version and treat the opening like any other wall penetration. The comparison is on the open versus closed page.
A short sizing note
LOD1414, a 14 inch diamond gable vent is 14 by 14 inches across the points that define the square. The visual height is the diagonal, so it takes more vertical room than a square of the same side. Check both the width and the point-to-point height against the gable. The sizing page gives a width range for appearance only.
Pair it with
Pair it with a simple wall so the diamond stays the accent. Two diamonds stacked in one gable usually look busy. If you want a softer accent, a round is calmer. The install overview covers fastening and paint.