An engagement ring is a very pensoral thing and over the years trends have changed. Popular styles usually change about every 10 to 15 years.  Wedding rings in the 40's and 50's tended to be white gold then into the 60's and 70's they tended to be yellow gold. Different gemstones started being used in the 80's and 90's  and the newest trend has been a yellow and white gold combination as well as the new chocolate diamonds and black diamonds. Sapphires and rubies are frequently used in combination with diamonds for wedding rings.  It's all a matter of what you want.