You should not opt for a color grade lower than G or H because it increases a yellowish tint in the stone. Another important thing to look for when choosing a marquise cut diamond ring is its clarity. The unique cut of marquise cut diamonds can make any inclusions visible compared to round diamonds or other diamond cuts. It is better that you choose a marquise cut diamond with a lower clarity grade as it has fewer inclusions and will hide them effectively.
Besides, you need to look into several important properties of a marquise diamond such as its symmetry, length to width ratio, bowtie effect, or any inclusions before making a purchase. You should also choose a ring setting that provides adequate protection to the stone especially its pointed edges. V-prong settings are ideal, as it can shield the stone from any impacts or falls preventing chipping and scratches.