Using the term "size" when relative to diamonds implies that a diamond is sold or categorized by measurements of length or width, this of course is not true. Diamonds are actually valued and categorized by the mass or carat weight.
What Really Is a Carat?
The term carat is a unit of measurement indicating the weight or mass for a diamond, the name was derived from the use of carob seeds. Ancient jewelers used carob seeds to balance their scales and determine how much a diamond weighed. One carob seed was the smallest unit of measurement for a diamond. Carob seeds were used as weights on precision scales because of their reputation for having a uniform weight. Today the carat is a universally accepted metric measurement.
A full or exact 1 carat diamond is 200 milligrams or 1/5 of a gram. There are 100 carat points to a full carat as there are 100 cents to 1 dollar. Half a dollar is 50 cents and half a carat is 50 carat points or .50ct for short. Diamond carat weights are grouped in to weight category ranges, for example the 1/2ct range is considered .45ct to .57ct. Use the following chart to learn the accepted carat weight groupings when considering your diamond engagement ring or diamond jewelry purchase.
Accepted Carat Weight Groups
The term carat is a unit of measurement indicating the weight or mass for a diamond, the name was derived from the use of carob seeds. Ancient jewelers used carob seeds to balance their scales and determine how much a diamond weighed. One carob seed was the smallest unit of measurement for a diamond. Carob seeds were used as weights on precision scales because of their reputation for having a uniform weight. Today the carat is a universally accepted metric measurement.
| Carat | Group |
|---|---|
| 1/4 ct | 0.23 ct - 0.28 ct |
| 1/3 ct | 0.29 ct - 0.37 ct |
| 3/8 ct | 0.38 ct - 0.44 ct |
| 1/2 ct | 0.45 ct - 0.57 ct |
| 5/8 ct | 0.58 ct - 0.68 ct |
| 3/4 ct | 0.69 ct - 0.82 ct |
| 7/8 ct | 0.83 ct - 0.95 ct |
| 1 ct | 0.96 ct - 1.10 ct |
| 1 1/4 ct | 1.23 ct - 1.28 ct |
| 1 1/3 ct | 1.29 ct - 1.37 ct |
| 1 3/8 ct | 1.38 ct - 1.44 ct |
| 1 1/2 ct | 1.45 ct - 1.57 ct |
Diamonds are valued on a per carat price and then multiplied by the actual carat weight to get the exact selling price. For example, a 1-carat diamond may be valued at $4000 per carat and if the diamond weighs exactly 1.05ct you would take $4000 and multiply it by 1.05ct to get the final selling price. $4000/ct x's 1.05ct = $4200 final selling price. This is a good tool to use when comparing diamonds for value.
You can take the selling price of a diamond and divide it by the exact carat weight to determine what you are paying "per carat" and then compare it to other diamonds you are considering.
Andrew Moquin
Jewelry Designer at Andrews Jewelers
Jewelry Designer at Andrews Jewelers
What Carat Weight Should I Choose?
Choosing the perfect carat weight for your diamond engagement ring should be based on several factors. This decision can't be made in a vacuum, consider the type of setting she likes, her finger size, and the type of person she's. Certain settings look better with smaller diamonds while others require bigger looking diamonds. A classic solitaire diamond engagement ring will accentuate the size of a diamond because the setting is thinner, so in the end you don't need as large a stone in this type of setting. A wider diamond engagement setting with many diamond side stones may require a larger looking diamond because the width of the ring is wider.
If her personality is more daring or outgoing then a larger diamond may be more suitable for her flair while on the other hand if she's shy or reserved then a medium to smaller diamond may be more appropriate to her style. Also consider her finger size, a smaller finger size (size 5.50 or smaller) does not require as large a diamond to look big on her finger. A larger finger size (7.50 and larger) can afford to have a larger setting style or diamond size worn on it.
The two months salary guideline is a very good place to start when trying to decide what size diamond is best for you. Take your monthly salary and double it and this is usually an acceptable amount to invest on your diamond engagement ring. Next you can decide what is more important cut, clarity, & color, or carat weight. If you want the biggest diamond your money can buy while maintaining a good quality consider an SI2/SI1 and I or J color.
In the end the best way to decide what is best for her is to discuss what she is dreaming of. If you are planning a surprise proposal then read our Engagement Ring Handbook for ideas on how to discuss diamonds with her.
The two months salary guideline is a very good place to start when trying to decide what size diamond is best for you. Take your monthly salary and double it and this is usually an acceptable amount to invest on your diamond engagement ring.
Andrew Moquin
Jewelry Designer at Andrews Jewelers
Jewelry Designer at Andrews Jewelers
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