A smaller engagement ring on a small size hand can look normal while a small diamond wedding ring on a large hand can look overpowered.
The round butterfly ring - cut is also popular so much so that it is often wrongly named as beeing brilliant cut.
a flawless diamond earrings is no more beautiful to the unaided human eye than a grade in the middle of the scale. Once again, extremely subtle differences in clarity are very important to determine rarity, but only affect beauty when in the very low end of the scale.