Diamonds, sapphires and all gemstones come in a range of sizes. Colloquially, the Carat Weight is used to describe the stone's size. This can be misleading since the Carat Weight specifically refers to the weight of a stone in metric carats. The metric carat is divided into 100 points, one hundredth of a carat is a point. Gemstones are weighed to a thousandth of a carat, and rounded to the nearest point, or hundredth. Carat is abbreviated to "ct" in descriptions.
Carat Weight specifically refers to the weight of a stone in metric carats
A more accurate way to determine the size of a gemstone is through their measurements, Length x Width x Height, this gives a more definitive size in millimeters (mm). Categorizing gemstones through carat weight is a good way to generally determine the size of a desired stone. It has also been popularized by the idea that the larger the carat weight is equal to the increased rarity and value.
Typically the larger the carat the higher the price tag, as the stone becomes larger so does the price per carat.
But there are other contributing factors to the value of a gemstone, like the color, cut, and clarity. By taking into account all the factors of a stone the value and it's rarity are determined.
When considering Diamonds vs. Sapphires one should take into account the gemstone's density. Sapphires have a different chemical composition which contributes to their density and specific gravity.
A 1ct sapphire will appear smaller than a 1ct diamond, but generally Sapphires are less expensive per carat compared to diamonds
A 1ct sapphire will appear smaller than a 1ct diamond, which you can see by comparing the measurements below. Generally Sapphires are less expensive per carat compared to diamonds, so they can be an economic choice if the carat weight and size are a priority.
- 1.55ct / 7.23 x 7.01 x 4.64mm Brilliant-cut Round Diamond
- 1.55ct / 6.83 x 6.54 x 4.40mm Brilliant-cut Round Sapphire
The Shape and Cut of a gemstone can also be a contributing factor to the visual size. Generally speaking, Pears, Ovals and Marquise shapes will optically look larger than a Round, Cushion or Trillions of the same carat weight.
1.55ct / 7.23 x 7.01 x 4.64mm Brilliant-cut Round Diamond
1.55ct / 6.83 x 6.54 x 4.40mm Brilliant-cut Round Sapphire