DIAMOND CARAT WEIGHT
Diamond Carat Weight Measures a Diamond’s Apparent Size
In simple terms, diamond carat weight measures a diamond's weight.
A metric 'carat' equals 200 milligrams. Each carat is divided into 100 'points,' allowing for very precise measurements to the hundredth decimal place. Jewelers might describe diamonds under one carat by their 'points' alone. For example, a diamond weighing 0.25 carats might be called a 'twenty-five pointer.' Diamonds over one carat are referred to in carats and decimal points, like a 1.08 carat diamond being described as 'one point oh eight carats.'
Generally, the price of a diamond increases with its carat weight, as larger diamonds are more rare and sought-after. However, two diamonds of the same carat weight can vary significantly in value and price, influenced by three other aspects of the 4Cs: Color, Clarity, and Cut.
While carat weight is important, remember that a diamond's overall value is determined by all of the 4Cs, not just its carat weight.
This short video explains carat weight and shows how diamonds are weighed in GIA’s lab on an extremely precise electronic scale.
To grasp what a diamond carat measures, it's useful to know the history of the carat system. Originally, carat weight was based on the carob seed, as early gem traders used these consistent seeds as counterweights in their scales. Now, a carat is universally defined as the same milligram weight globally.
Certain diamond weights, like half a carat, three-quarter carat, and one carat, are often referred to as "magic sizes." There's a minimal visual difference between a diamond weighing 0.99 carats and one that is exactly one carat. However, the price difference between these two sizes can be substantial.