According to American etiquette experts, the bride's wedding ring is worn on her left-hand ring finger first, with her engagement ring placed on top of it.
The reasoning behind this placement is to facilitate the exchange of wedding rings during the wedding ceremony. Traditionally, the bride wears her engagement ring on her right hand so her husband can place the wedding ring on her left. After the ceremony, she removes the engagement ring and places it on top of her wedding band. One of the ways to recall the traditional placement is to remember that a bride wears her wedding ring closer to her heart.
Some women have their engagement ring and wedding ring welded together before the wedding so that the engagement ring doesn't slide around. Others leave their engagement ring on their right hand wear their wedding ring on the left. Some brides and grooms choose to place both the wedding ring and the engagement rings on at the same time during the ceremony. The groom needs to sure that he knows what order they are worn in. In some countries, like Poland, Greece and Colombia, both brides and grooms wear their rings on the third fingers of their right hands.