Almost nobody selects a ring with a wedding dress in mind, because the ring arrives first, and the dress is chosen months later by a different person with different advice. The two decisions still land on the same hand on the same day, and photographers spend a good portion of that day shooting them together. The gap between those two decisions is where most of the mismatches happen.
Order of Purchase and Its Consequences
The sequence is fixed by custom. A proposer buys a ring, often without input, and the wearer then chooses a gown that has to accommodate whatever is already on her finger. That order gives the ring priority in theory. In practice, the gown covers more surface area, sets the color temperature of every photograph, and determines how much of the hand is visible at all.
