Carat Weight and Diamonds

Of all of the 4 C’s of diamond grading, everyone knows about carat weight (shortened to cd).  This unit of measure originated from the measurement of a carob seed.  This seed always had a consistent size and weight, so it was used as a standard, and is still used today.  A lot of people consider diamond carat a unit of size, but refers rather to weight. The carat weight for 1 cd. is equivalent to 200 milligrams.

After raw diamonds are extracted, they start out much larger than the finished product (as much as 2/3 of the total weight can  be lost).

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Diamond Sizes Calculator Chart







As a raw stone they have many flaws, inclusions, and blemishes.  Just like gold and silver need to be refined after being mined, diamonds require a lot of cutting and polishing before being ready for use.

The way the diamond is cut during this process has a great impact on how much light is reflected back up towards the table (top) of the stone.  After cutting, most diamonds end up being less than one carat, and the typical size for a diamond engagement ring is approximately 1/3 of a carat weight.

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Carat Weight and Rarity

Diamonds with a larger carat weight (above 1 carat) tend to be very rare, and hence more expensive.  Celebrities that pay $90,000 for a ring are the individuals that purchase diamonds with all rare properties.  However, a diamond cut and setting can make a diamond seem larger or smaller than its carat weight.  Also the distance of the top surface of the diamond affects the overall appearance as well.

How Big of Carat Weight Should You Choose?

Just because a diamond is large in size does not mean it will look stunning.  It could have many imperfections and scratches which would diminish its beauty.   In order to have a completely clean look, all 4 Cs need to be carefully considered.

It is best to suit the ring to the woman, as a 5 carat diamond ring on a petite woman’s hand’s could look awkward, and vice versa. Diamond earrings, necklaces, or pendants could also present the same problem. The size of the ring can affect the appearance of the diamond.  Not all settings will be able to hold all shapes and sizes of stones, so make sure to check your setting (if it’s been chosen first) as to not make a mismatch.

There are other ways to make the stone appear larger than it actually is.   A marquise or emerald shape can make it seem bigger, especially if used in combination with a high setting (such as a Tiffany setting).  Another way is to use accent stones around the side or around the setting, as very small diamonds cost significantly less than a center stone.

The Reliability of the Carat Weight

While nowadays we see the carat as a fixed-value unit, it should stand noted how much it varied throughout history. There’s a legend that at some point in history, gold, gems, and diamonds merchants found out that the carat weight can vary slightly depending on the species of carob that was used for the seeds. So they found out which seeds weighed the least and started using these as units of measurement in their stores (mainly in the US and in the UK).

The result was that consumers themselves became aware of this and began buying their own carob seeds on the way to a diamond purchase. They then used the seeds, which were supposed to be of the original carat weight, to test the precious stone merchant’s honesty. If the diamond seller’s carats were lighter, then the customer would be entitled to a preferential rate of exchange. This deal implied that the heavier seeds were used when the merchant wanted to purchase, and the lighter ones when the customer intended to buy diamonds.

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The Carats of the Most Expensive Diamonds

Ever wondered what the most expensive diamonds’ carat weight is? We have and are able to say that it’s truly fascinating how price estimates vary at the top of the diamond world. For instance, an average 2 carat diamond ring could end up costing far more than a 5 carat diamond ring. For this, the right conditions need to be met: the prices depend on prestige, on who wore the diamond, on whether the diamond has a slight (yellow, blue, green, or pink) hue, and on the condition of the diamond prior to its cutting.

Here are the 5 most expensive diamonds in the world and their respective weights:

  • De Beers Centenary Diamond. This diamond is worth about $100 million. Care to guess how many carats a diamond worth $100 million has? Precisely 85 CD. That’s equivalent to approximately 55 grams. It was discovered in the Premier Mine in South Africa.
  • Hope Diamond. You’ve probably heard people asking about this one: how many carats is the hope diamond? Well, to quickly answer that question: 52 carats. Its estimated value is at around $200 or $250 million. It’s so expensive because it was once owned by King Louis XIV of France. Now it rests at the National Museum of Natural History in Washington D.C.
  • The Cullinan I. Part ofvalue the original Cullinan (valued at $400 million), this one weighs 4 carats or about 106 grams. If you think that’s a lot, then you’re right. Yet that’s less than half of the original loose, uncut Cullinan. It’s actually the largest polished diamond in the whole world right now. Along with its brother the Cullinan II, it’s in the possession of the British Crown.
  • The Sancy Diamond. This one is of an un-estimated value, somewhat over the $400 million mark. The problem with this 23 carat diamond is that it was currently completely lost for a few hundred years. It once belonged to the Great Moghuls, after which it was passed along from king to king, to prince and to princess, until eventually it got to the Apollo Gallery in the Louvre.
  • The Koh-I-Noor Diamond. You probably saw this oval precious coming. It weighs in at 105.602 carats and it’s valued as being priceless. This one currently rests on the diamond cushions of the British crown, where it went after the Punjab conquest in 1849.



While each woman will have her preference of shape, weight, color, and clarity, at the end of the day, it all depends on what looks good on the woman’s finger.  Just as a dress or blouse will look different on every woman, so will the ring with its sparkle.

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