Below are some examples of edge work and shapes for table tops or shelving. Table tops designed for protection of existing tables are typiically cut out of 1/4 clear glass with a sanded smmoth edge. The edge work displayed below is usually found on glass that is 3/8" or thicker.
Some table tops or shelves have radiused corners. The best way to get the radius is to imagine, or use a pattern to create a square corner and mark and measure from the point where the curve starts on both sides of the corner. See diagram below ...
The same rule would apply to clipped corners. Use this handy tool to determine the size of your clipped corners.