Traditional / Public Domain — a fundamental block-within-a-block construction technique
A center square set on point within successively larger frames of triangles, creating a diamond-within-a-square effect. This versatile unit appears as a component in many traditional blocks and as a standalone pattern. Precision with bias edges is the key challenge.
The Square-in-a-Square is one of the fundamental building blocks of quilt design, dating to at least the early 1800s. The technique of setting a square on point and adding corner triangles is the basis for dozens of traditional patterns, from simple diamond designs to complex medallion quilts.
This block was essential in Amish quilting tradition, where a single diamond (square on point) in bold colors against a dark background was the centerpiece of many quilts. The simplicity of the shape allowed Amish quilters to showcase their spectacular hand quilting. The technique also appears in English and Welsh quilting traditions.
Also known as: Diamond in a Square, Economy Block, Jewel Block, Framed Square
finished Block Size
12"
seam Allowance
1/4"
grid Basis
Concentric rounds (center + 2 rounds of corner triangles)
units Required
1 center square + 4 triangles round 1 + 4 triangles round 2
All measurements include 1/4" seam allowance unless noted.
| Piece | Fabric | Cut Size | Qty | Notes |
|---|---|---|---|---|
| Center Square | Center | 5 1/4" x 5 1/4" | 1 | On-point center |
| Round 1 Triangle | Frame 1 | 5" x 5" | 2 | Cut each once diagonally — yields 4 triangles |
| Round 2 Triangle | Frame 2 | 7" x 7" | 2 | Cut each once diagonally — yields 4 triangles |
Cut your center square and two Round 1 squares. Cut each Round 1 square once diagonally to make 4 triangles total.
Tip: Spray starch all fabrics before cutting. Bias edges (the diagonal cuts) will stretch without it.
Find the center of one triangle's long edge and the center of one side of the center square. Pin right sides together, matching centers. Sew with a 1/4" seam. Repeat on the OPPOSITE side of the center square. Press seams toward the triangles.
Tip: Always sew opposite sides first, then the remaining two. This keeps the unit square.
Sew the two remaining Round 1 triangles to the remaining sides. Press toward triangles. Trim the unit to square it up — the center diamond should float with equal margins on all four sides.
Cut two Round 2 squares diagonally to make 4 triangles. Repeat the same process: sew two opposite triangles first, press, then add the remaining two.
Press all seams toward the outer triangles. Square up the block to 12 1/2", keeping the center diamond perfectly centered.
Tip: Use a large square ruler and align the 45-degree line with the center diamond's points.
All edges of this block are on the bias until the final trim. Handle gently — don't stretch or pull. Spray starch helps maintain stability.
See how this traditional pattern looks in different color combinations.
Medallion center — one large block surrounded by borders
Side by side — creates a tessellated diamond field
With sashing — each diamond framed individually