Crystals begin to stick together and slowly add layer upon layer to form a stone. A kidney stone may grow for months or even years before it causes a problem. Kidney stones don't all look the same. The color depends on what chemicals are in it. Most are yellow or brown, but they can be tan, gold, or black.
Stones can be round, jagged, or even have branches.
They vary in size from specks to pebbles to stones as big as golf balls. Kidney stones can cause kidney damage. Whether there is damage and, if so, how much there is depends on the location of the stone in the urinary system. To avoid or minimize damage, it is important to eliminate stones that form and to prevent new ones from developing. Therefore, your family doctor may refer you to a urologist , a doctor who specializes in urinary diseases.