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Gram to Carat – How to convert g to ct
Whether you're buying diamonds, evaluating gemstones, or working on a school project, knowing how to convert grams to carats is essential. Carats are the universal unit of weight for gems like diamonds, rubies, and sapphires, and they directly affect value and certification. Jetcalculator’s Gram to Carat Converter makes this conversion instant and accurate. For other unit comparisons, check out our complete Unit Converter.
What is a Gram (g) and a Carat (Ct)
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Gram (g) is a standard metric unit of mass, equal to one-thousandth of a kilogram (1 g = 0.001 kg). It’s widely used in science, commerce, and everyday life. If you're working with smaller weights, you can also try our Gram to Milligram Converter, or scale up using the Gram to Kilogram Converter.
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Carat (ct) is a unit of mass specifically used for gemstones. One metric carat = 0.2 grams. The carat system has been standardized since 1907 and is used globally by gemologists and jewelers. Gem weight in carats is a major factor in determining a stone's value — especially for diamonds.
The conversion formula is simple and universal: Carat = Gram ÷ 0.2
Or: Carat = Gram × 5
Examples:
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1 gram → 1 × 5 = 5 carats
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0.3 gram → 0.3 × 5 = 1.5 carats
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2 grams → 2 × 5 = 10 carats
For fast results, use Jetcalculator’s Gram to Carat Converter, or explore other mass conversions using our Weight Converter.
Did You Know?
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Gram:
• The word “gram” comes from the Greek gramma, meaning "a small weight."
• In pharmaceuticals, medicine dosages often rely on sub-gram accuracy — hence the need for milligrams.
• Some kitchen scales now show weights in tenths of a gram to accommodate fine ingredients like spices or powders. -
Carat:
• The term “carat” originates from the carob seed, which was historically used as a balance weight for gemstones.
• One 1-carat diamond is 0.2 grams, about the weight of a paperclip.
• A 10-carat diamond can cost over $100,000 USD, depending on cut, clarity, and color.
• Gemologists measure diamonds to hundredths of a carat, using precision tools for certification (e.g., 1.03 ct).
Crown Jewels and Carats: The Story of the Koh-i-Noor
One of the most famous gemstones in history, the Koh-i-Noor diamond, has been passed through the hands of emperors, maharajas, and monarchs. Originally mined in India, this legendary stone was said to weigh 186 carats before being cut in the 19th century by British jewelers.
Today, the Koh-i-Noor rests in the Tower of London as part of the British Crown Jewels, with a final weight of 105.6 carats — equivalent to 21.12 grams.
This single stone carries the weight of centuries — not just in carats, but in history, conflict, and symbolism.
Conclusion
Converting g to ct is essential when dealing with gemstone weights, whether you're shopping for jewelry, studying mineralogy, or working in gem certification. With Jetcalculator’s Gram to Carat Converter, you can get precise results instantly and understand the significance of carats in global gem trading. For more tools, try our Conversion Tool and discover how simple it is to convert units across the board.
Want to explore more unit conversions related to grams and gemstones? Try these:
