GEMSTONE CARAT WEIGHT CHART
Gem weight is measured in metric carat scale. One carat is equivalent to 200 milligrams (0.20 grams) and is divided into 100 points for precision. This applies not only to diamonds but to colored stones, too. A sapphire weighing half of a carat may be referred to as 0.50 carats.
Carat weight and size are not the same and these two must not be confused for two reasons:
1. Two gemstones of the same type, carat weight, and shape may appear different due to differing cuts. The gems with deeper cuts are likely to appear smaller than the other.
2. Gem have different densities (mass per unit volume). Sapphires, for instance, are denser than diamonds, meaning one-carat sapphires would appear smaller than one-carat diamonds.
The best way to visualize the size of a gemstone is by its dimensions, the top diameter in particular.
The carat weights given for standard gem sizes in the chart apply to diamonds cut to ideal proportions. Usually, when working on standard gem sizes, gem cutters will cut colored gems with greater volume than diamonds so there will be different weights as those listed below.
SHOULD YOU BUY BASED ON CARAT WEIGHT OR GEM SIZES?
When buying gems it’s important to know what you need them for, as this will help you decide on the determining factors. If you’re buying a stone for an existing jewelry setting it’s best to buy by size and not by estimating weights. If you are buying a stone to have a setting custom-made then you buy the stone that most appeals to you.
It’s good to note weight and size when buying diamonds or other stones but don’t limit yourself to these characteristics alone. Consider the gems as a whole, even the way it looks to the naked eye.
Frequently Asked Questions
However, it is important to remember that a diamond’s beauty is not affected by mere carat weight alone. There is also clarity, and cut and color. There is also a tip of going for a size (or its diameter or width) just below the larger stone you wish for. The cost of diamonds will vary for each 0.5 ct.
At the same time, the gems specific gravity (that is, how much it weighs in water) is not the same. Specific gravity of a diamond is 3.52. Other gems like amethyst are lighter weight with the specific gravity of 2.66. Sapphire is 4.0. All gemstones weigh differently. A 1 carat diamond will not look the same size as a 1-carat amethyst or sapphire.
So the correct measure of the gems’ worth is by millimeter size, like 4×6 mm or 5×7 mm. Thereby a 4×6 mm sapphire will look actually the same size as a 4×6 mm amethyst, regardless of the gems’ weights.