A diamond-shaped knitting pattern is popular on sweaters and vests. The diamond pattern is made by knitting and purling, increasing on each row until you get to the mid-row on the diamond, then working the pattern in reverse to complete the diamond.
argyle
Domino Knitting, is, I think, what is being sought here. This is modular knitting in which squares with diagonal ridges are knitted together serially. See Vivian Hoxbro's book, "Domino Knitting". http://www.amazon.com/Domino-Knitting-Technique-Vivian-Hoxbro/dp/193149911X/ref=sr_1_2?ie=UTF8&s=books&qid=1246215513&sr=8-2#
A diamond-shaped poem is called a "diamond poem" or a "diamond shaped poem."
Knitting is a method of making fabrics from yarns. They can be shaped as they are made. Knitting is a common method of making sweaters, hats, socks, blankets, scarves, and gloves. It is possible to make smoother fabrics with knitting than it is with crocheting.
There are many places where one can purchase a heart shaped diamond. A heart shaped diamond can be purchased at many popular stores such as Zales and Kay Jewelers.
See the image above. The snake has a rattle as well as a diamond-shaped pattern on its skin.
A template used for a type of needlework decoration where small regularly spaced gathers are stitched into a diamond shaped pattern
Calf
The diamondback rattlesnake got its name from the diamond shaped pattern on its back.
a rhombus
the walnut
Plaster bagworm
Kites are often shaped like diamonds, or modified diamond shapes.