When it comes to diamond rings, for many, the middle stone's size is the most important factor. While the diamond's measures are related to its carat weight and cut, there are some more factors influencing the perceived size.
Have a look at the rings on the left: At first glance, it may appear as if the upper one was adorned with a bigger diamond. As the graphic on the right shows, however, this is not the case.
Diamonds of different carat weights may appear slightly smaller or larger depending on the ring size: A one-carat diamond will look larger when worn on a small hand as compared to a bigger finger and hand.