# Carats to Centigrams (ct to cg) Source: https://www.unitconvertercalculator.com/weight/carats-to-centigrams/ **1 ct = 20 cg** One carat equals exactly 20 centigrams. The carat, standardized at 200 milligrams (0.2 grams) since 1907, converts cleanly to centigrams because a centigram is one hundredth of a gram. This makes the arithmetic straightforward: 0.2 grams multiplied by 100 centigrams per gram equals 20 centigrams per carat. ## Formula Apply the conversion factor ## Conversion Table | Carats (ct) | Centigrams (cg) | |---|---| | 0.25 ct | 5 cg | | 0.5 ct | 10 cg | | 1 ct | 20 cg | | 2 ct | 40 cg | | 3 ct | 60 cg | | 5 ct | 100 cg | | 10 ct | 200 cg | | 25 ct | 500 cg | | 50 ct | 1000 cg | | 100 ct | 2000 cg | | 250 ct | 5000 cg | | 500 ct | 10000 cg | | 1000 ct | 20000 cg | | 5000 ct | 100000 cg | ## Units ### Carat (ct) A carat is a unit of mass equal to exactly 200 milligrams (0.2 grams), used for measuring gemstones and pearls. Adopted internationally in 1907 by the Fourth General Conference on Weights and Measures. ### Centigram (cg) A centigram is one hundredth of a gram. It is a metric unit rarely used in everyday life but appears in some scientific and educational contexts. ## Background While jewelers work in carats and laboratory scientists occasionally use centigrams, the two units rarely overlap in daily practice. A 1-carat diamond weighs 20 centigrams, and a 5-carat sapphire weighs 100 centigrams - exactly 1 gram. This conversion is most useful in gemological education and in countries where centigrams still appear in pharmaceutical or chemical documentation. ## Good to Know The centigram is a product of the metric system's strict decimal logic, but it never gained the traction that the centimeter did in length measurement. In the world of gemstones, the carat's own sub-units (points, where 100 points equal 1 carat) serve the same purpose as centigrams would, making the centigram redundant for jewelers. The gemstone industry essentially invented its own parallel decimal system within the carat. ## FAQ ### How many centigrams are in one carat? One carat equals exactly 20 centigrams. This comes from 1 carat being 0.2 grams and 1 centigram being 0.01 grams: 0.2 divided by 0.01 equals 20. ### What is a centigram? A centigram is one hundredth of a gram (0.01 g). It is a metric unit that sits between the milligram (0.001 g) and the decigram (0.1 g). While rarely used in everyday life, it appears in some scientific and pharmaceutical contexts. ### Why is the carat exactly 0.2 grams? The modern metric carat was standardized at the Fourth General Conference on Weights and Measures in 1907 at exactly 200 milligrams (0.2 grams). This rounded value was chosen to approximate the historical carat, which was based on carob seeds and varied between roughly 189 and 215 milligrams depending on region. ## Non-Frequently Asked Questions ### If I weighed my morning coffee in centigrams, how many carats would it be? A standard cup of black coffee weighs about 237 grams or 23,700 centigrams. That is 1,185 carats. If your morning brew were made of diamonds instead of beans, you would be drinking roughly 12 million dollars worth of coffee. The flavor would probably be worse. ### Has anyone ever accidentally confused carats with centigrams at a jewelry store? If a customer thought a 20-centigram diamond was a 20-carat diamond, they would expect a stone roughly the size of a walnut - one of the largest diamonds ever found. The actual 20-centigram stone is a modest 1-carat gem. The ensuing price discussion would be memorable. ### Is the centigram the most forgotten metric unit? The centigram shares the obscurity podium with the decigram, decameter, and hectometer. You will almost never see centigrams on a kitchen scale, in a recipe, or at a doctor's office. 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