This plunge bra gives very good cleavage. The band is quite long, but it has very little stretch to it (it is satin rather than elastane), and therefore can be worn by a 28. You could go up one cup and still be very comfortable, depending on what type of neckline you are wearing.
Beautiful bra. Gives a great shape and cleavage. Tight band. The cups are a bit shallow for a 28DD, they go very low, but do not cut in, which make this bra suitable for ultra low-cut tops. Otherwise I would suggest a 30D for everyday wear.