Engagement rings

An engagement ring indicates that the person wearing it is promised to be married, especially in Western cultures.
In the United Kingdom, Ireland, North America and South Africa engagement rings are traditionally worn only by women, and rings can feature diamonds and/or other gemstones. In other cultures both men and women wear matching rings. In some cultures, engagement rings are also used as wedding rings.
Engagement represents a formal agreement to future marriage. Rings can be bought by the man, the woman, the couple together, or by each partner for the other.
Diamonds are a sign of steadfast, enduring love. This is because diamonds are unequalled in its strength and bauty. Diamonds really last for ever.
Diamonds are so versatile that it can be worn with any outfit - from jeans to cocktail dress. 
The tradition of giving a ring to a woman to indicate that she was promised as someone's bride, existed for centuries, but adding a  diamond is a relatively recent innovation. Diamond engagement rings first became popular in the 1930s. By 1965, 80 percent of all new brides in the United States wore diamond rings. 
The history of the diamond engagement ring
Anthropologists believe the tradition of  a man presenting his prospective bride with an engagement ring upon acceptance of his marriage proposal, started with the Romans whose wives wore rings attached to small keys, indicating their husbands' ownership. In 1477,  Archduke Maximillian of Austria commissioned the very first diamond engagement ring on record for his betrothed, Mary of Burgundy. This sparked a trend for diamond rings among European aristocracy and nobility.
The Victorians made ornate engagement ring designs that mixed diamonds with other gemstones, popular. These rings were often crafted in the shapes of flowers and were dubbed “posey rings.” Diamond rings crafted during the Edwardian era continued the tradition of pairing diamonds with other jewels.
Diamonds were so rare and expensive that people of lesser means could not afford it. That was until the discovery of the  African diamond mines in the 1870's. The De Beers Company was the sole owner and operator of these newly discovered mines in South Africa. In the 1930s, when demand for diamond rings declined in the U.S. during hard economic times, the De Beers Company began an aggressive marketing campaign using photographs of glamorous movie stars swathed in diamonds. Within three years, the sales of diamonds had increased by 50 percent.
In 1947, De Beers launched its now classic slogan, "A  Diamond is Forever" which ensured that diamond sales rocketed. The implied durability of a diamond conveyed the meaning in the European psyche that marriage is forever.  A diamond's purity and sparkle have now become symbols of the depth of a man's commitment to the woman he loves in practically all corners of the world. 
Over the years, the most popular cut for diamond engagement rings has always been the round brilliant (a shape that resembles that of a cone and provides maximized light return through the top of the diamond), consisting of 58 facets that divide the stone into a top and bottom half. Runners-up in popularity are the princess cut, the emerald cut and the oval cut, with the cushion cut quickly gaining popularity as a recent trend.
Read more at the American Gem Society
Interested in reading more about the history of engagement rings?