How much would a diamond the size of a grain of rice be worth?

The value of a diamond is determined by the 4 Cs: carat weight, cut, color, and clarity. A diamond the size of a grain of rice would likely be less than 0.01 carats, which is considered a melee diamond. Melee diamonds are typically lower in value due to their small size and are often used as accent stones. Therefore, the value of a diamond this size would depend on its specific characteristics, but it would generally be on the lower end of the price scale.