What is the difference between a carat and a karat?
What is a Carat?
A carat is a unit of weight for gemstones, where one carat equals 1/5 of a gram, or 200 milligrams. 142 carats equals one ounce. Carats are divided into 100 units, called points . One carat is divided into 100 points. A half carat stone is 50 points, a quarter carat 25 points. The important thing to note is that carat is a unit of weight, not a unit of size. A one carat stone that is dense will be smaller than a one carat stone that is less dense. For example, sapphires are denser than diamonds, so a one carat sapphire will be smaller than a one carat diamond. In pricing, there is a big difference between one carat total weight (1 ct TW) and a one carat stone. For example, a one carat diamond is much more valuable than a grouping of smaller diamonds that add up to one carat.
What is a Karat?
A karat is not a unit of weight. The word karat refers to the amount of gold in a particular item. Karats are measured in units of 24, where 24 karat gold is pure gold. 18 karat gold is 18 parts gold and 6 parts alloys such as copper, nickel, silver or zinc. 14 karat gold is 14 parts gold and 10 parts alloy.
Gemstones
Natural gemstones are found in nature. Laboratory-created stones , as the name implies, are made in a laboratory. These stones, which also are referred to as laboratory-grown, [name of manufacturer]-created, or synthetic, have essentially the same chemical, physical and visual properties as natural gemstones. Laboratory- created stones do not have the rarity of naturally colored stones and they are less expensive than naturally mined stones. By contrast, imitation stones look like natural stones in appearance only, and may be glass, plastic, or less costly stones. Gemstones may be measured by weight, size, or both. The basic unit for weighing gemstones is the carat, which is equal to one-fifth (1/5th) of a gram. Carats are divided into 100 units, called points . For example, a half-carat gemstone would weigh .50 carats or 50 points. When gemstones are measured by dimensions, the size is expressed in millimeters (for example, 7x5 millimeters).
Diamonds
A diamond's value is based on four criteria: color, cut, clarity, and carat. The clarity and color of a diamond usually are graded. However, scales are not uniform: a clarity grade of "slightly included" may represent a different grade on one grading system versus another, depending on the terms used in the scale. Make sure you know how a particular scale and grade represent the color or clarity of the diamond you're considering. A diamond can be described as "flawless" only if it has no visible surface or internal Includedions when viewed under 10-power magnification by a skilled diamond grader. As with other gems, diamond weight usually is stated in carats. Diamond weight may be described in decimal or fractional parts of a carat. For example, ".30 carat" could represent a diamond that weighs between .295 - .304 carat. Some retailers describe diamond weight in fractions and use the fraction to represent a range of weights. For example, a diamond described as 1/2 carat could weigh between .47 - .54 carat. Diamond Carat: The term carat is the unit of weight for diamonds. One carat is divided into 100 points. A half carat stone is 50 points, a quarter carat 25 points. In pricing, there is a big difference between one carat total weight (1 ct TW) and a one carat stone. For example, a one carat diamond is much more valuable than a grouping of smaller diamonds that add up to one carat.
Diamond Color
If you are looking for a diamond for an engagement ring or pendant, find one that is the whitest white. Of the Four Cs of diamond valuation, many experts name color as the number one consideration. Diamond colors are graded on a simple system, beginning with "D" for colorless and move down the alphabet to stones with traces of color to stones with visible shadings. Stones with poor color can be found towards the end of the alphabet.
A diamond's ability to reflect and refract light is dependent on its whiteness. When white light enters the diamond, part of the ray is reflected back to the observer's eye, but the rest of the light penetrates the stone. Refraction occurs when the ray is deflected toward the center of the stone, then bounced back to the surface. The whiter the color, the greater the reaction.
Since color differences can be so subtle, they are impossible to determine by the untrained eye. To grade a diamond, gemologists often place it on a white background next to another diamond that has been previously graded.
|
Diamond Color Scale |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
Z |
Fancy Colors |
| Colorless |
Near Colorless |
Faint Yellow |
Very Light Yellow |
Light Yellow |
Diamond Clarity
- Flawless (FI): Flawless diamonds show no blemishes or inclusions when examined under 10x magnification
- Internally Flawless (IF): IF stones show no inclusions and only insignificant blemishes under 10x magnification.
- Very Very Slightly Included (VVS 1 and VVS 2 ): VVS diamonds contain minute inclusions that are difficult for even a skilled grader to locate under 10x magnification. In VVS 1 , they are extremely difficult to see, visible only from the pavilion, or small and shallow enough to be removed by minor repolishing. In VVS 2 , they are very difficult to see.
- Very Slightly Included (VS 1 and VS 2 ): VS diamonds contain minor inclusions ranging from difficult (VS 1 ) to somewhat easy (VS 2 ) to see under 10x magnification.
- Slightly Included (SI 1 and SI 2 ): SI stones contain noticeable inclusions which are easy (SI 1 ) or very easy (SI 2 ) to see under 10x magnification. These diamonds are sometimes called "eye clean" because they appear flawless to the naked eye.
- Included (I 1 , I 2 , and I 3 ): I-grade diamonds contain inclusions which are obvious under 10x magnification, and can usually be seen with the unaided eye. These flaws can seriously affect the stone's potential durability, or are so numerous they affect the transparency and brilliance of the stone.
|
Diamond Clarity Scale |
FL |
IF |
VVS 1 |
VVS 2 |
VS 1 |
VS 2 |
SI 1 |
SI 2 |
I 1 |
I 2 |
I 3 |
|
Flawless-
Internally Flawless |
Very Very Slightly
Included |
Very Slightly
Included |
Slightly Included |
Included |
Diamond Cut
In talking about the cut of a diamond, we are referring to the proportions of the diamond as opposed to its shape (round, marquise, pear, princess, etc.). The cut has the greatest influence on the fire and brilliance of a diamond. A well cut stone with the correct angles and number of facets will reflect and refract light back out the top of the diamond for maximum brilliance. A stone that is cut too deep or too shallow may appear lifeless or dark when compared to a correctly cut stone.
 The cut of a diamond as a value factor, refers to its proportions , symmetry and finish . It is not to be confused with its shape. Proportion refers to the angles and relative measurements of a polished diamond. More than any other feature, proportions determine a diamond's optical properties. Studies have shown that table size, crown angle, and pavilion depth have a dramatic effect on a diamond's appearance.
Symmetry is a grading term for the exactness of shape and placement of facets. Variations in symmetry include off-center culets and tables, poor facet alignment, misshapen facets, out-of-round girdles, and wavy girdles.
Diamond Shapes
Shapes other than the standard round brilliant shown above are called fancy shapes or fancy cuts. Their names are based on their shapes. The best known are the heart , marquise , pear-shaped cut , emerald - cut , oval , and radiant .
Pearls
Natural or real pearls are made by oysters and other mollusks. Cultured pearls also are grown by mollusks, but with human intervention; that is, an irritant introduced into the shells causes a pearl to grow. Imitation pearls are man-made with glass, plastic, or organic materials. Because natural pearls are very rare, most pearls used in jewelry are either cultured or imitation pearls. Cultured pearls, because they are made by oysters or mollusks, usually are more expensive than imitation pearls. A cultured pearl's value is largely based on its size, usually stated in millimeters, and the quality of its nacre coating, which gives it luster. Jewelers should tell you if the pearls are cultured or imitation. Some black, bronze, gold, purple, blue and orange pearls, whether natural or cultured, occur that way in nature; some, however, are dyed through various processes. Jewelers should tell you whether the colored pearls are naturally colored, dyed or irradiated. |
