Draw an equilateral triangle, half the size of the diamond you want for your design, on tagboard. (Use a protractor to measure the three 60-degree angles, and draw the sides using a ruler.) Cut out the triangle with scissors. Use either two equilateral triangles or a one-piece diamond shape to make the diamond.
Trace around the cut-out triangle to make a second triangle. Cut out the second triangle from the tagboard. If you want to make a one-piece diamond shape, place the triangles with their bases touching, and apply tape to hold them in place. Trace around this diamond shape, making a one-piece diamond on the tagboard.
Measure the one-piece diamond and a piece of white paper to ensure the diamonds will line up properly. Your tessellation should end up with the tip of the one-piece diamond, or the base of a trianglem touching the edges of the paper.
Mark faint pencil lines on the white paper to help you lay out your diamond shapes. Mark the center of the white paper. You have a choice to either draw a straight line across the width of the paper going through the marked center point or centering a diamond over the center point and drawing lines across the width of the paper that would touch the tips of the diamond. In the first case, the center of the design will consist of two diamond points touching together. In the second case, the center of the design will serve as the center of a diamond.
Draw each line the height of the diamond if you're using the one-piece shape, or the height of a triangle if you're using two equilateral triangles. Beginning at the center, trace the first shape according to the decision you made regarding the center design.
Move the pattern to the right, and trace the second shape. Continue until you reach both sides of the paper. The design should touch both sides with either the side tip of the diamond, or the base of a triangle.
Move the pattern up or down one line. Trace the pattern to fit in the already established spacing. Continue until you have filled the entire piece of white paper.
Color in the diamonds with your choice of colors. The most common method would be to use two different colors, similar to an argyle design. Start at the center of the tessellation. Check to determine which column is the focal point, then color this column with a colored pencil, crayon or marker. The next column will consist of the diamonds that fit next to the first column of diamonds. Color this column a second color. Continue alternating colors until you have completed the tessellation.