Carat vs. Karat: Understanding the Difference
Gold Karat vs. Carat – What’s the Difference?
Despite sounding similar, karat and carat measure completely different things.
- 💎 Carat (ct) – Measures gemstone weight.
- 🔶 Karat (K) – Measures gold purity.
In the UK, gold is often labelled in carats (ct) rather than karats (K), but both refer to the same gold purity measurement.
What is Carat (ct)?
Carat (ct) is the unit of weight used for diamonds and gemstones, helping to determine their value and rarity. Unlike what many people assume, carat does not measure a stone’s size, but rather its weight.
How Much Does One Carat Weigh?
- 1 carat = 200 milligrams (0.2 grams), about the weight of a small paperclip.
- 5 carats = 1 gram, meaning even a large-looking diamond is surprisingly light.
Carat Weight vs. Size: Bigger Doesn’t Always Mean Heavier
While higher-carat diamonds tend to be larger, their actual perceived size is influenced by:
- The cut – A well-cut diamond reflects light efficiently and can appear bigger.
- The shape – Elongated shapes like oval, pear, or marquise diamonds can create the illusion of a larger stone compared to a round diamond of the same carat weight.
- The setting – A halo or bezel setting can make a diamond appear larger than its actual weight.
Fun Facts About Carat Weight
- The word “carat” comes from the carob seed, historically used by traders as a standard weight for gemstones.
- The world’s largest diamond ever found was the Cullinan Diamond, weighing a massive 3,106 carats before being cut into the British Crown Jewels.
- A 1-carat round diamond typically measures 6.4mm in diameter, while an emerald-cut diamond of the same weight may be 5.5mm x 7mm.
- Diamond prices increase exponentially with carat weight due to rarity.
What is Karat (K)?
Karat (K) measures the purity of gold in jewellery. Unlike carat (ct), which measures gemstone weight, karat refers to the percentage of gold in an alloy.
Understanding Gold Purity
| Karat (K) | Gold Purity (%) | Features |
|---|---|---|
| 24K | 99.9% | Pure gold, soft, rarely used in rings. |
| 18K | 75% | Rich in colour, durable for jewellery. |
| 14K | 58.3% | Durable, ideal for everyday wear. |
| 9K | 37.5% | Hard-wearing, budget-friendly. |
Why is Gold Mixed with Other Metals?
- Copper – Adds warmth, creating rose gold tones.
- Silver & Palladium – Lightens gold, producing white gold.
- Zinc & Nickel – Enhance durability and modify shades.
Hallmarks: Ensuring Gold Purity & Authenticity
Gold jewellery is often hallmarked, meaning it has been tested and stamped to confirm its gold content.
- ✅ Gold Purity Mark – Confirms the gold percentage.
- ✅ Assay Office Stamp – Identifies the official testing body (e.g., London, Birmingham).
- ✅ Maker’s Mark – A symbol representing the jeweller.
Making the Right Choice
Understanding the difference between carat and karat ensures you make an informed jewellery purchase. Whether you're searching for a dazzling diamond engagement ring or a timeless gold wedding band, Baldwin Jewellery has a collection designed to suit every style. Explore our range today! 💎✨