Traditionally, cocktail rings were worn to events like cocktail parties (hence the name), as they were seen as bolder and more elaborate than your average ring. But now, as fashion has become more fluid and less constricted by trends, a cocktail ring provides a stylish finish to both casual and formal looks.    Team a pearl or opal cocktail ring with jeans and a tee to emphasise its beautiful simplicity, or complement silver or gold cocktail rings with smaller, more delicate rings and other accessories.     Bring out the vibrant blue of an aquamarine cocktail ring with a pair of aquamarine studs, or the velvety green of an emerald cocktail ring with a dainty emerald pendant for a sleek yet balanced look. Or provide a sophisticated backdrop to a diamond cocktail ring with a delicate pair of garnet studs.