How to repair cracked glass ?

I have an outside "street" light in my garden. One of the glasses is cracked. The wattage of the bulb is 60W, so virtually no heat is involved. The glass is so ornate that a flat piece of glass could not be used to replace it. I suspect that the lamp may now be discontinued and I would like to continue using the light, but I want to be sure it is both safe and weatherproof. The glass is curved, 4" wide at its widest point and 3.5" long.