To maintain the quality of your bees wax, here's a few things to be aware of when melting:
Temprature
Heating the wax to tempratures above 85ºC (185ºf) may discolour it. The melting point of beeswax is 62-65ºC (143 - 149ºf). If melted in water at excessive tempratures, hot steam can cause partial saponification and ruin the wax
Water type
Melting in soft water (like rain water) if preferable. Acidifying the water with something like 0.1 % vinegar can protect the wax.
Container material
wax heated in a container made with iron, brass, zinc and copper in it may cause a reaction that will discolour the wax. Stainless steel, aluminum or enameled steel, tempered glass & ceramic pots should be okay.