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A square set on point within a square frame — the architectural cornerstone of Amish quilting
Also known as: Square in a Square · Center Diamond
The Diamond in Square is the simplest way to set a square on point — adding four corner triangles to a rotated center square creates a second square frame. It's the foundational unit of Amish quilt geometry and a component of dozens of complex patterns.
| Fabric | Cut | For |
|---|---|---|
| Center diamond | 1 square at 9¼″ | center squarecut generous — the unit is squared up after the triangles go on |
| Side triangles | 2 squares at 7¼″ | squares — cut each once on the diagonal for the 4 side triangles |
Sew a triangle to each side of the center square (opposite sides first), press outward, then square up — the center's corners should float ¼″ inside the trimmed edge.
The Diamond in Square block — or Square in Square, as it's also called — is most closely associated with Amish and Mennonite quilting traditions, where it appears in both simple and extraordinarily complex forms. The classic "Center Diamond" Amish quilt is essentially one enormous Diamond in Square: a large central square set on point, surrounded by a wide border of a contrasting solid color, creating a bold geometric statement from the simplest possible construction.
Amish quilters, working from the late 19th century through the early 20th century, elevated the Diamond in Square to an art form. Lancaster County, Pennsylvania examples — in jewel-bright solid colors against black backgrounds — are among the most reproduced and imitated quilts in American textile history. Their geometry is so clean and their color choices so bold that they look as contemporary today as they did when first made.
Outside of Amish tradition, the Diamond in Square unit appears as a component in Storm at Sea, Variable Star variations, and as a recurring border motif. It's also a critical technical skill: adding accurate triangles to set a square on point without distortion requires careful cutting and pressing.
The center square can be any size. For each corner triangle, you need a square cut in half diagonally. The formula: (finished center diagonal ÷ 2) + ⅞" = triangle square size. This puts the straight grain on the outer edge of the finished block.
Sew a triangle to two opposite sides of the center square (top and bottom). Press outward. Sew a triangle to the remaining two sides (left and right). Press outward. The center square is now surrounded by triangles.
The assembled unit will be slightly rough on the outer edges. Trim to a perfect square using a quilting ruler. Leave ¼" beyond the corner points of the center diamond for the seam allowance.
For a true Diamond in Square block, add a plain square frame: sew four rectangles around the outside of the unit (or four more corner triangles for a second rotation). Press outward.
Amish tradition uses high-contrast solid fabrics — often a jewel-bright center diamond against a black or dark navy frame. For modern interpretations, the center square is the spotlight: use your best or boldest fabric there. The triangle frame should recede into the background.
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Multiple nested rotations — each diamond becomes a square, which becomes the center of a new diamond.
The same construction at quilt scale — one huge diamond filling the entire quilt center.
NiftyFifty quilters have been swapping blocks like this one since 1997. Browse our historical archive or join a new swap.
Browse quilt swaps →A complex arrangement of units creates rolling waves that seem to move across the quilt surface
Eight crisp star points emerge from four quarter-square triangle units — a pattern that rewards precise piecing
Four triangles meeting at the center — the essential unit for star points, hourglasses, and pinwheels
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