The most secure settings for a marquise diamond are those that protect its pointed ends, which are the most vulnerable to chipping. A V-prong setting, where the prongs are shaped in a "V" to cover the tips, is ideal for this purpose. Additionally, a six-prong setting, with four prongs securing the sides and two V-shaped prongs protecting the tips, can offer stability and security. Bezel settings, which encircle the diamond with a thin metal rim, can also provide excellent protection for marquise diamonds.