This unit is sometimes called Diamond in a Square as it essentially a square, turned on point (hence ‘diamond’) inside another square. It is found in a wide variety of blocks, usually in the corners or the centre, and is useful as a ‘spacer’ block between busier blocks and as a border unit – either as ‘cornerstones’, where a plain square doesn’t quite work, or to make a pieced border. You can find a downloadable free step-by-step tutorial on making these units here.
There are two different methods for making these units. One is simply cutting the centre square and four triangles to stitch around it, the other is a ‘quick-piecing’ method using five squares. The larger centre square has the smaller squares placed on the corners, one at a time, you then stitch across the diagonal of the smaller square and cut away the excess – having first checked that you have stitched the correct diagonal. The trinalges and square method can seem a bit daunting at first because the edges of the triangles are longer than the ides of the square, but there is a useful tip for lining everything up correctly. Both these methods are detailed in the free tutorial.
If you press the seams to one side and out towards the triangles, away from the square, then you will get a nice clear ‘X’ to mark the point where the seams meet – something to aim for when stitching other units to this one.
But what sizes of squares and triangles do you need to cut? You can download a free pdf with tables for different sizes of unit from 2 – 12 inches here. You can have a lot of fun playing with the colourings of this unit wherever and however you choose to use it and you can find more information in my blog about it (which will be coming soon!).