A pedestal sink is often used in a small bathroom where space is at a premium. The sinks can look elegant, and often feature large bowls. However, if there is a chip or break, both the bowl and pedestal have to be replaced.
Pedestal sinks attach to the wall, and most of the weight is supported by the wall hanger. The pedestal is placed below, adding extra support and a decorative element that hides plumbing. The sinks often have a modern design.
The sinks and pedestals are designed to complement each other, creating a unified image. Sometimes sinks are flat on the bottom, and other times they have a slope or a curve. Each pedestal is designed to accommodate the particular sink that was designed especially for that pedestal. Even slight differences will cause rocking and eventual cracking, besides looking awkward and unattractive.
It's possible that a qualified repair shop could repair chips and cracks in a pedestal sink, eliminating the need for replacement. Repairs to fibreglass fixtures are the most common, but porcelain and ceramic repairs may also be possible. Look into this option before replacing the entire sink and pedestal.