1 ct diamond with wedding band
Here is the popular cathedral setting solitaire ring. It is available in 14k white or yellow gold, 18k yellow gold with a platinum head or all platinum. They will take a round diamond from 1/2 ct up to 3 ct or in a variety of other diamond shapes.
The width of the band normally increases to balance with a larger size and/or different shape of the center diamond. For example, a 1/2 ct round diamond should be set in a 4 mm wide band, and a 3/4 ct round diamond in a 4.25 mm wide band.