I think you are probably thinking about a Cushion cut or a Radiant cut…they have a similar facet appearance to that of a marquise, but are square or rectangular in shape. A cushion is my first guess because it does not have straight square sides, but rather a bit rounded…and can be almost oval at times, depending on the cut of the stone. Have a look at some cushions and see if that has the look you like.

Tim
Emma Parker & Co.

adiamondisforever.com

click on design, the design your own. it’ll bring up a window where you can design a ring. has all the different diamond cuts right on the website

princess cut? maybe