What is a Carat?
In the world of gemstones, the "carat" (ct) is the standard unit of mass. Not to be confused with "karat" (the purity of gold), the carat has a fascinating history dating back to ancient markets.
The History of the Carat
The word comes from the "carob" seed. In ancient times, traders used carob seeds as counterweights on their scales because the seeds were remarkably consistent in weight.
Converting Carats to Grams
Today, the "metric carat" is standardized:
- 1 carat = 0.2 grams
- 5 carats = 1 gram
Carat vs. Size
It's a common misconception that carat weight equals visual size. Different gemstones have different densities (specific gravity). For example:
- A 1-carat Diamond will look larger than a 1-carat Sapphire because sapphires are denser.
- A 1-carat Emerald will look larger than both because it is less dense.
Key Takeaways
- 1 ct = 200 mg
- Carat measures weight, not size
- Density determines how big a stone looks for its weight