Converting Grams to Carats (g to ct) is the standard language of the jewelry trade. While gold and silver are often weighed in grams (or troy ounces), gemstones like diamonds, rubies, and sapphires are weighed in Carats. The metric carat is defined as exactly 200 milligrams or 0.2 grams. This means that 1 Gram is equal to exactly 5 Carats.
*1 Carat = 0.2 Grams.
Master Weight Converter
The Formula
Multiply the number of Grams by 5:
Grams × 5 = Carats
Example
If a raw diamond weighs 2 Grams:
2 × 5 = 10 Carats
From Common Weight to Gemstone Value
Did you know? A standard US nickel weighs exactly 5 grams. If that nickel were a giant diamond, it would be a massive 25-carat stone! Remembering that 1 gram equals 5 carats makes it easy to visualize gemstone weights.
Frequently Asked Questions
One gram is equivalent to exactly 5 carats. This is a worldwide standard used by every major jewelry house. Because gems like diamonds, rubies, and sapphires are so dense and valuable, we use this smaller unit to ensure every tiny bit of weight is accounted for.
Just multiply by 5!
• 0.2 Grams = 1 Carat
• 0.5 Grams = 2.5 Carats
• 1 Gram = 5 Carats
• 10 Grams = 50 Carats
Before modern scales, merchants used the seeds of the carob tree to weigh gems because the seeds were almost always the same size. Eventually, scientists realized they needed a more “official” weight, so they decided that 5 carats would equal exactly 1 gram to keep the math simple for everyone.
A 5-carat stone is exactly 1 gram. While 1 gram feels very light when you’re holding a paperclip or a grape, a 1-gram diamond is actually quite large and would be considered a very high-value “statement” piece of jewelry!