Diamond in Square Quilt Block
A square set on point within a square frame — the architectural cornerstone of Amish quilting
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.
History & Background
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.
Step-by-Step Instructions
Cut your center square and side triangles
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 the side triangles
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.
Trim to a square
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.
Add an outer frame (optional)
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.
Tips & Techniques
- Cut triangle squares slightly oversized and trim after assembly rather than cutting to exact size upfront — bias edges are prone to stretching during sewing.
- Press every seam outward from the center. Inward pressing at the center diamond creates bulk and distorts the points.
- The straight grain of the triangles should run along the outer edges of the finished block, not along the diagonal. This prevents the outer edges from stretching when the block is assembled into a quilt.
Color & Fabric Selection
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.
Variations & Related Patterns
Square in Square in Square
Multiple nested rotations — each diamond becomes a square, which becomes the center of a new diamond.
Amish Center Diamond
The same construction at quilt scale — one huge diamond filling the entire quilt center.
Quick Facts
Put it to use
NiftyFifty quilters have been swapping blocks like this one since 1997. Browse our historical archive or join a new swap.
Browse quilt swaps →Related Guides
Storm at Sea Quilt Pattern
AdvancedA complex arrangement of units creates rolling waves that seem to move across the quilt surface
Ohio Star Quilt Block
IntermediateEight crisp star points emerge from four quarter-square triangle units — a pattern that rewards precise piecing
Quarter-Square Triangle (QST) Quilt Block
IntermediateFour triangles meeting at the center — the essential unit for star points, hourglasses, and pinwheels