<P> Like all jewelry, the price for an engagement ring varies considerably depending on the materials used: the design of the ring, whether it includes a gemstone, the value of any gemstone, and the seller . The price of the gemstones, if any, in the ring depends on the type and quality of the gem . Diamonds have a standardized description that values them according to their carat weight, color, clarity and cut . Other gemstones, such as sapphires, rubies, emeralds, have different systems . These may be chosen to honor a family tradition, to use family heirlooms, to be unique, to be socially responsible (they are not associated with blood diamonds or the pollution caused by gold mining and cyanide process), to fit the individual's stylistic preferences, or to manage cost . Synthetic stones and diamond substitutes such as cubic zirconias and moissanites are also popular choices that are socially responsible and reduce cost while maintaining the desired appearance . </P> <P> The idea that a man should spend a significant fraction of his annual income for an engagement ring originated from De Beers marketing materials in the mid-20th century in an effort to increase the sale of diamonds . In the 1930s, they suggested that a man should spend the equivalent of one month's income in the engagement ring; later they suggested that he should spend two months' income on it . In 2012, the average cost of an engagement ring in USA as reported by the industry was US $4,000 . In the UK, estimates of the average cost of an engagement ring range from £ 1200 to £ 2000 . </P> <P> One reason for the increased popularity of expensive engagement rings is its relationship to human sexuality and the woman's marriage prospects . In the United States, until the Great Depression, a man who broke off a marriage engagement could be sued for breach of promise . Monetary damages included actual expenses incurred in preparing for the wedding, plus damages for emotional distress and loss of other marriage prospects . Damages were greatly increased if the woman had engaged in sexual intercourse with her fiancé . Beginning in 1935, these laws were repealed or limited . However, the social and financial cost of a broken engagement was no less: marriage was the only financially sound option for most women, and if she was no longer a virgin, her prospects for a suitable future marriage were greatly decreased . The diamond engagement ring thus became a source of financial security for the woman . </P> <P> The online purchase of engagement rings is growing, disrupting the market for the diamonds by bringing greater transparency to an industry that has traditionally relied on opacity . Online diamond retailers and e-commerce platforms include Rare Carat, Blue Nile, Brilliant Earth, and Costco . </P>

Who was the first person known to wear a diamond engagement ring