Convert grams to carats in seconds
1 g ÷ 0.2 = 5 ct
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Ever held a diamond ring and wondered about its weight? That sparkling stone's mass isn't measured in regular grams – jewelers use carats. But what does that mean for your kitchen scale measurements? Let's crack this unit conversion nut together.
Unit definitions
What is a gram (g)?
Description: The gram is your go-to metric unit for small mass measurements. From sugar in recipes to letter weights at the post office, it's everywhere.
Symbol: g
Common uses: Cooking, postal services, scientific measurements
Definition: 1/1000th of a kilogram, the SI base unit for mass
What is a carat (ct)?
Description: The carat is the VIP of gemstone measurements. Developed specifically for precious stones, it's crucial in jewelry making and gemology.
Symbol: ct or ct
Common uses: Diamond weights, pearl measurements, gem trading
Definition: 200 milligrams exactly (0.2 grams) since 1907
Conversion formula
The math here is straightforward once you remember this golden ratio:
1 carat = 0.2 grams → 1 gram = 5 carats
So if you have:
- Grams to carats: carats = grams × 5
- Carats to grams: grams = carats ÷ 5
Not a math fan? Our converter above does the heavy lifting. But understanding the formula helps when you're comparing jewelry prices or checking lab reports.
Example calculations
- Your lab-grown diamond weighs 0.85 grams. How many carats is that?
0.85g × 5 = 4.25ct
That's equivalent to a princess-cut stone about 10mm wide - A vintage necklace has 18ct sapphires. What's their total weight in grams?
18ct ÷ 5 = 3.6g
Fun fact – sapphires are denser than diamonds, so 3.6g would be smaller in size than 3.6g of diamonds
Conversion tables
Grams to carats
| Grams | Carats |
|---|---|
| 0.1 | 0.5 |
| 0.2 | 1 |
| 0.5 | 2.5 |
| 1 | 5 |
| 2 | 10 |
| 3 | 15 |
| 4 | 20 |
| 5 | 25 |
| 10 | 50 |
| 20 | 100 |
Carats to grams
| Carats | Grams |
|---|---|
| 0.5 | 0.1 |
| 1 | 0.2 |
| 2 | 0.4 |
| 5 | 1 |
| 10 | 2 |
| 20 | 4 |
| 50 | 10 |
| 100 | 20 |
| 200 | 40 |
| 500 | 100 |
Historical background
The carat's story begins with carob seeds – those brown pods you sometimes see in health stores. Ancient gem traders used these remarkably consistent seeds as counterweights on balance scales. The word "carat" itself comes from the Greek "keration," meaning carob seed.
In the early 20 th century, things got standardized. The 1907 Fourth General Conference on Weights and Measures in Paris set 1 metric carat at exactly 200mg. Before this, a carat might weigh 205mg in London but 197mg in Florence – nightmare for international trade!
Interesting facts
- The Cullinan Diamond – Largest gem-quality rough diamond ever found (3,106.75ct or 621.35g) was cut into pieces for British crown jewels
- Carat vs. Size – Two 1ct diamonds can appear different sizes based on cut. A shallow cut makes stones look larger but reduces sparkle
- Pearl Special – Pearls use "grains" (1 grain = 0.25ct) but often convert to carats for international sales
- Gold Connection – While unrelated to weight, 24-karat gold is pure gold. 18k gold contains 18/24 parts gold (75%)
- Carat Subdivisions – Jewelers use points (1ct=100 points). A "50-pointer" means 0.50ct
FAQ
Carats provide a standardized unit for small gemstone weights, making comparisons easier in the jewelry trade. Imagine describing a diamond as 0.2 grams vs 1 carat – the latter is more intuitive for industry professionals.
No, that's a common mix-up! Karat measures gold purity (24K = pure gold), while carat measures gemstone weight. Both terms originate from the carob seed, but they evolved differently.
While not precise, you can estimate using size charts for specific gem types. A 1-carat round diamond typically measures 6.5mm in diameter. But for accurate measurements, always use a calibrated scale.
Yes, the metric carat (200mg) is standardized worldwide since 1907. Some historical systems used slightly different values, but modern jewelry uses the universal 1ct=0.2g standard.
In the US, most engagement diamond center stones range between 1-2 carats (0.2-0.4g). But remember – cut quality affects perceived size more than weight alone!