Diamonds — The Four C's
Carat

When we buy sugar, we think in terms of price per pound. If we buy gold we will think in terms of grams or ounces. These are units for measuring weight. In diamonds and other gemstones, we measure their weight in carats. The word "carat" originated in a natural unit of weight: the seeds of the carob tree. Diamonds were traditionally weighed against these seeds until the system was standardized and one carat was fixed at 0.2 gram (one fifth of a gram).
One carat is divided into 100 "points" so that a diamond of 25 points is described as quarter of a carat, or 0.25 carat (ct). Think in terms of pennies in a dollar and you'll get the picture.
When it comes to the weight of diamond, "2 + 2" usually does not equal "4." A one carat diamond can be quite a bit more valuable than two half carat diamonds even though their total weight is the same. Why? Because the larger stones are more rare and therefore more valuable. It's a simple matter of supply and demand. One "dollars and cents" example: Let's say we have two half carat diamonds that are F in color and SI2 in clarity and let's say they sell for $1,500 each, or $3,000 for the two of them. Now let's take a single one carat diamond of the same exact quality, (the carat weight is identical to the two half carat stones). That single one carat diamond could cost upwards of $5,500.
It is also worth noting that a one carat round brilliant cut diamond is not twice the visual size of a half carat round brilliant cut diamond. Nor is a two carat diamond two times larger visually than a one carat. The chart at the right shows a comparison of round brilliants of various carat weights. Although they are not shown actual size, they do accurately reflect the comparative difference in "look."
One carat is divided into 100 "points" so that a diamond of 25 points is described as quarter of a carat, or 0.25 carat (ct). Think in terms of pennies in a dollar and you'll get the picture.
When it comes to the weight of diamond, "2 + 2" usually does not equal "4." A one carat diamond can be quite a bit more valuable than two half carat diamonds even though their total weight is the same. Why? Because the larger stones are more rare and therefore more valuable. It's a simple matter of supply and demand. One "dollars and cents" example: Let's say we have two half carat diamonds that are F in color and SI2 in clarity and let's say they sell for $1,500 each, or $3,000 for the two of them. Now let's take a single one carat diamond of the same exact quality, (the carat weight is identical to the two half carat stones). That single one carat diamond could cost upwards of $5,500.
It is also worth noting that a one carat round brilliant cut diamond is not twice the visual size of a half carat round brilliant cut diamond. Nor is a two carat diamond two times larger visually than a one carat. The chart at the right shows a comparison of round brilliants of various carat weights. Although they are not shown actual size, they do accurately reflect the comparative difference in "look."

In terms of value, carat weight can be more complicated
than you would expect. Again, let's take that one carat F/SI2 round
brilliant cut diamond, valued at $5,500 roughly. A 0.99ct round
brilliant cut stone of equal quality might cost $4,600 per carat or
about $4,500. A thousand dollars less for a stone that will look the
same in size and quality, right? Not if the cutter has anything to say
about it. His job depends upon him being able to cut that stone so that
it weighs in at 1.00 carat or more since there is a price per carat
break at the magic one carat boundary. (This boundary happens at
regular points throughout the weight/price charts by the way.) So you
can see why it might be extremely difficult to find a 0.99ct diamond,
and why if you did, you would expect to pay a premium well above the
0.90ct price bracket.
The 1.00ct boundary is a psychological one. The value of a one carat diamond over a 0.95ct stone of equal quality (for example) is something you must decide. To some, this is a valid point of concern, to others, Color and Cut may be more critical factors in choosing a diamond where budget is of some constraint.
Our interest is in your satisfaction with your choice. We will help and advise you in how to get the maximum value and "pride of ownership" when buying a diamond, or any fine gem for that matter.
The 1.00ct boundary is a psychological one. The value of a one carat diamond over a 0.95ct stone of equal quality (for example) is something you must decide. To some, this is a valid point of concern, to others, Color and Cut may be more critical factors in choosing a diamond where budget is of some constraint.
Our interest is in your satisfaction with your choice. We will help and advise you in how to get the maximum value and "pride of ownership" when buying a diamond, or any fine gem for that matter.