Depending on composition kidney stones will vary in color, shape, and size. If you are able to miss the passing of your kidney stone then you are a champion.
Kidney stones are usually brown or yellow but can also be gold or black. They are actually urinary excretions that have become crystallized in the urethra.
It is a good idea to urinate in a sieve to catch the stone. Stones come in different colors depending on the composition. Most are yellow or brown but they can also be black, gold or tan.