While the weight of diamond bracelet is important, it doesnt necessarily provide the "perceived size" of diamond store. A shallow cut diamond will have a greater diameter, and will therefore look larger.
Dont be fooled into buying diamond earrings that are said to be .25 points. They are NOT a quarter of a carat, and will be so small that they should only be used as accents to other stones or the gold itself.
The most popular GIA Certified Diamond shape has been the round brilliant because people believed it to be an "ideal cut" that displayed the most brilliance and sparkle in a diamond store.