Carat Weight Converter
Carat price, grams, and points from stone weight.
What it does
Carat weighs diamonds in fifths of a gram: a one carat stone is 0.2 g, and points slice each carat into a hundred tradable slivers. Price follows weight times a per carat rate that quality sets.
The tool above takes carats with price per carat. It returns total price, grams, and points.
The default 1.5 carats at $6,000 runs $9,000.00 with 0.3 g and 150 points. The 2 carat case at $4,000 runs $8,000.00.
Gemological weight standards fix the carat at 0.2 grams exactly, and trade guidance repeats the hundred point split. Per carat rates climb with size and quality, which the adjustable input respects.
Weight never equals worth alone: cut brilliance, color grades, and clarity plots move real prices. Weigh precisely, price from current sheets, and keep carat weight apart from gold karat purity.
How to use
- Type the carat weight.
- Type the price per carat.
- Read total price first.
- Read grams beside it.
- Read points last.
- Compare per gram rates.
Formula
- carats
- Diamond weight in metric carats.
- $/ct
- Market rate per carat in dollars.
- points
- Hundredths of a carat.
GIA diamond weight standards define the metric carat at exactly 0.2 grams with 100 points per carat. Jewelers Vigilance Committee guidance mirrors the same weights for trade descriptions. Price per carat varies by quality, so totals estimate from the entered rate.
Worked example
Example: 1.5 carat stone
Defaults: 1.5 ct at $6,000 per carat.
- Stone: 1.5 carats at $6,000 per carat.
- Grams: 1.5 x 0.2 = 0.3 g.
- Points: 1.5 x 100 = 150 points.
- Price: 1.5 x 6000 = $9,000.00.
- Check: 0.3 g x 5000 = $9,000 per gram rate.
- Tool shows $9,000.00, 0.3 g, 150 points.
Reference table
| Carats | Grams | Points |
|---|---|---|
| 0.5 | 0.1 g | 50 |
| 1 | 0.2 g | 100 |
| 1.5 | 0.3 g | 150 |
| 2 | 0.4 g | 200 |
Limits
- Weight math only.
- Rates vary by quality.
- Rounded display past milligrams.
- Gold karat is separate.
Common mistakes
- Reading points as carats.
- Mixing carat with karat.
- Pricing from weight alone.
- Weighing on kitchen scales.
- Ignoring per carat size curves.
Try it yourself
Quick checks. Answers sit tucked under each question.
2 carats at $4,000 per carat?
$8,000.00 with 0.4 g and 200 points.
0.5 carats weight only?
0.1 g with 50 points at any rate.
0 carats?
Under 0.01 falls below melee scales: enter 0.01 to 100.
Questions
Grams per carat?
0.2 grams exactly, or 200 milligrams. A 1.5 carat stone weighs 0.3 g.
Points meaning?
Hundredths of a carat: 150 points is 1.50 carats. Jewelers quote points under one carat.
Price from weight?
No, weight only. Cut, color, and clarity move price per carat far more than size.
Bigger cheaper per carat?
Price per carat climbs with size: per carat rates already bake rarity in.
Carat or karat?
Carat with a C weighs; karat with a K purifies gold. Different rulers, easy mix.
Scale precision?
Milligram scales read 0.001 g; carat answers need that third decimal.