When loose diamonds is cut too shallow, light leaks out of the bottom, brilliance is lost and the diamond store appears watery, glassy and lifeless.
The most popular wholesale diamonds shape have been the round brilliant because people believed it to be an "ideal cut" that displayed the most brilliance and sparkle in diamond store.
While the weight of a titanium ring is important, it doesnt necessarily provide the "perceived size" of a diamond store. A shallow cut diamond will have a greater diameter, and will therefore look larger.