"A diamond is forever." This slogan was coined by copywriter Mary Frances Gerety for De Beers over 70 years ago, in one of the world's most famous and successful marketing campaigns of all time.
To this day diamonds are the gem du jour for special occasions, milestones, and especially proposals of marriage, thanks to Gerety. Her slogan skyrocketed the popularity of diamonds for engagement rings after the great depression.
The cost per carat, or the weight of a gemstone, is based upon a stone’s rarity. The rarer the stone, the more expensive. Emeralds, rubies and sapphires are in fact more rare and far more expensive than diamonds. However, thanks to clever marketing campaigns and an insane amount of sparkle, diamonds are the number one selling precious gemstone. Nevertheless, diamonds have long been considered a valuable stone, and for good reason.
A bit of history:
The word diamond was derived from the Greek word “adamas” meaning unbreakable, untamable, indestructible. The hardest stone that has ever existed in nature, diamonds were formed several million years ago from carbon at extraordinarily high pressures. Measuring in at a ten on the Mohs Scale (an empirical gauge of the hardness of minerals) the diamond is the hardest known mineral on earth. Impressive.