Throughout the century, diamonds have remained expensive, thanks to the relative rarity of the stone and near-monopolistic control of the diamond industry. Most of the major producers belong to a marketing cartel that has kept a tight rein on supply, distribution and prices. Consequently, it’s difficult for consumers to find bargain-basement sales and great discounts.

What does a carat cost?
Retail prices vary from one area of the country to another, but a rough estimate of the cost of a diamond is as follows:

  • 1/2-carat:
    $1,000 to $3,000
  • ¾-carat:
    $2,500 to $5,000
  • 1-carat:
    $3,500 to $10,000 and up

Nationally, the average cost of a diamond engagement ring is about $1,800.

Another way to think about price is by differences in grade. It’s estimated that a stone will increase in value 5 to 10 percent for each boost in color grade. It may jump 15 to 20 percent for each increase in clarity grade. A “best” cut may be worth 30 percent more than a “fair” cut. Finally, increases in carat weight cause the price of diamonds to leap geometrically; a one-carat stone of the same quality as a half-carat stone has twice the carat size but may be three times as expensive.