Two Words That Sound the Same but Mean Completely Different Things
If you have ever been confused by 'carat' and 'karat,' you are not alone. These two terms sound identical when spoken, are often misspelled even by professionals, and measure completely different things. Here is the simplest possible explanation.
Carat (ct) = Diamond Weight
- What it measures: The weight of a diamond or gemstone
- One carat equals: 0.200 grams (200 milligrams). A 1.00 carat diamond weighs exactly one-fifth of a gram
- Abbreviation: ct (e.g., 1.50 ct)
- Total Carat Weight: TCW refers to the combined weight of all diamonds in a piece (e.g., a tennis bracelet with 3.00 TCW)
- Origin: Named after carob seeds, which ancient gem traders used as counterweights because of their remarkably consistent weight
Karat (K or kt) = Gold Purity
- What it measures: The proportion of pure gold in a gold alloy
- Scale: 24 parts total. 24K = pure gold (100%). 14K = 14 parts gold out of 24 (58.3%). 10K = 10 parts gold out of 24 (41.7%)
- Abbreviation: K or kt (e.g., 14K or 14kt)
- Common karats: 10K (41.7% gold), 14K (58.3% gold), 18K (75% gold), 22K (91.7% gold), 24K (99.9% gold)
- Why not always 24K: Pure gold is too soft for jewelry. Alloying with copper, silver, and zinc adds strength for daily wear. 14K and 10K are the most popular for wearable jewelry
Quick Reference
- 'A 1.50 carat diamond in 14 karat gold' means: A diamond weighing 0.300 grams set in gold that is 58.3% pure
- Carat relates to GEMSTONES (weight)
- Karat relates to GOLD (purity)
- You can have a large carat diamond in a low karat gold, or a small carat diamond in a high karat gold — they are completely independent measurements
Common Confusion Points
- '18 carat gold' is technically incorrect but widely used in everyday language. The correct term is '18 karat gold'
- In many countries outside the US, 'carat' is used for both — context determines the meaning
- Jewelers know what you mean either way, so do not stress about using the wrong one in conversation