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Carat Conversion Table
This comprehensive carat conversion table shows how various units relate to carats, the unit for measuring precious stones. Use this reference for quick conversions between carats and other common mass units.
| Conversion | To Unit | Multiplier |
|---|---|---|
| Carats to kilograms | Kilograms | 0.0002 |
| Carats to grams | Grams | 0.2 |
| Carats to milligrams | Milligrams | 200 |
| Carats to micrograms | Micrograms | 200000 |
| Carats to tonnes | Tonnes | 2e-7 |
| Carats to pounds | Pounds | 0.000440925 |
| Carats to ounces | Ounces | 0.00705479 |
| Carats to stones | Stones | 0.0000314946 |
| Carats to grains | Grains | 3.08647 |
| Carats to hundredweight (short) | Hundredweights (short) | 4.40925e-6 |
| Carats to hundredweight (long) | Hundredweights (long) | 3.93683e-6 |
| Carats to slugs | Slugs | 0.0000137044 |
This carat conversion reference table provides accurate conversion factors for both metric (SI) units and imperial units. All values are based on internationally recognized standards for maximum precision in scientific and engineering applications. Note that 1 carat is exactly 0.2 grams.
What is a Carat?
The carat (symbol: ct) is a unit of mass equal to 200 milligrams (0.2 grams). It is used for measuring the mass of gemstones and pearls. The word "carat" comes from the carob seed, which was historically used as a standard for weighing precious stones due to its uniform weight. Today, the carat is a standardized unit used worldwide in the jewelry industry.
The carat is subdivided into 100 points, so a diamond weighing 0.5 carats can also be described as a 50-point diamond. Our carat conversion tool helps you easily convert between carats and other units of mass. For example, 1 carat equals 0.007 ounces or 0.00044 pounds.
What is the SI of Carat?
The carat is not an SI unit, but it is accepted for use with the SI. The SI base unit for mass is the kilogram. However, in the context of gemology and jewelry, the carat is the standard unit for measuring precious stones:
- 1 carat = 0.2 grams = 200 milligrams
- 1 kilogram = 5,000 carats
- 1 gram = 5 carats
- 1 milligram = 0.005 carats
What are Carats Used For?
Carats are used exclusively in the jewelry and gemological industries for measuring the mass of precious stones like diamonds, rubies, sapphires, and emeralds. As the international standard for gemstone measurement, carats provide a precise way to specify stone weight:
Jewelry Appraisal
Determining the value of gemstones in rings, necklaces, and bracelets. For example, a 1-carat diamond engagement ring versus a 0.5-carat diamond.
Gemstone Trading
International commerce in precious stones relies on carat measurements for pricing. For example, rough diamonds are often sold by the carat at wholesale markets.
Mining Industry
Assessing the yield of diamond and gemstone mines. For example, a mine producing 10,000 carats of diamonds per day.
Scientific Research
Gemological laboratories use carats to classify and document specimens. For example, measuring the mass of a newly discovered mineral sample.
Etymology and History
The word "carat" comes from the Greek "keration," meaning carob seed. Ancient jewelers used carob seeds as counterweights in balance scales because they were believed to have uniform weight. This practice led to the development of the carat as a unit of measurement for precious stones.
In 1907, the carat was standardized at exactly 200 milligrams (0.2 grams) at the Fourth General Conference on Weights and Measures. This international standardization eliminated variations in carat weight that existed between different countries and established a universal measurement system for the gemstone trade.
Frequently Asked Questions
Why is the carat used for measuring gemstones?
The carat is used because it provides a precise, standardized measurement for small masses typical of gemstones. Historically derived from carob seeds, the carat was formalized in 1907 as exactly 200 milligrams. This standardization ensures consistency in international gemstone trading and prevents disputes over stone weights.
How accurate is the carat definition?
The carat is precisely defined as exactly 200 milligrams (0.2 grams), making it one of the most accurately defined units in measurement. This definition is universally accepted and ensures that a 1-carat diamond has the same mass regardless of where it is measured in the world.
What's the difference between carat and karat?
"Carat" (ct) measures the mass of gemstones, while "karat" (K or kt) measures the purity of gold. For example, a 1-carat diamond weighs 0.2 grams, while 24-karat gold is pure gold. The similar spelling often causes confusion, but they refer to completely different properties.
How do I convert carats to other units?
Use our carat conversion calculators above, or multiply by the appropriate conversion factor. For example, to convert carats to grams, multiply by 0.2; to convert carats to milligrams, multiply by 200. For detailed instructions on converting carats to kilograms, visit our ct to kg converter.
What are common uses for carat conversion?
Carat conversion is primarily used in jewelry appraisal, gemstone trading, mining yield assessment, and gemological research. Whether determining the value of a diamond engagement ring or calculating the total yield of a diamond mine, our carat converter tool simplifies these specialized measurements.
How does carat conversion differ from other mass units?
The carat is specifically designed for measuring small masses typical of gemstones, with 1 carat equal to exactly 0.2 grams. This makes it much more precise for jewelry applications than larger units like kilograms or pounds. Our carat converter handles the specific needs of gemstone measurement with appropriate precision.
Can I convert very small or very large measurements in carats?
Yes, our carat converter handles both extremely small and large measurements with precision. For microscopic work, convert micrograms to carats (1 µg = 0.000005 ct). For large gemstone collections, convert carats to kilograms (1 kg = 5,000 ct). Our smart rounding feature ensures readable results for all scales.
Is your carat conversion tool free to use?
Yes, our carat conversion calculator is completely free with no registration required. Simply enter your value, select your target unit, and get instant, accurate results. We believe precise measurement conversion should be accessible to everyone, from jewelry enthusiasts to professional gemologists.