Carat weight is the weight of the diamond measured in carats. One carat is divided into 100 "points," so that a diamond of 75 points weighs 0.75 carats. Carat weight is the most obvious factor in determining the value of a diamond. But two diamonds of equal carat weights can have very different prices, depending on their quality. Diamonds of high quality can be found in all size ranges.
Since diamonds are measured by carat weight, and not size, two diamonds of the same weight could have different sizes. Why? If a diamond is cut too shallow it will have a larger diameter but a smaller depth. Likewise, if a diamond is cut too deep it will have a smaller diameter and thus appear smaller when viewed from the top.Cut is very important. A properly cut diamond will both yield a good face up size and sparkle well. For example, let's say you're interested in a 1.00ct round diamond. A poorly cut diamond that is really deep would only have a diameter of approximately 6.1mm. So not only are you short changed on the face up size, but you get a diamond that was not cut to it’s full potential and thus does not sparkle like it should.
Diamond Clarity
The Diamond Clarity is a measure of a diamond's internal flaws and impurities. A diamond that is virtually free of interior or exterior inclusions is of the highest quality, for nothing interferes with the passage of light through the diamond. To determine a diamond's clarity, it is viewed under 10 x magnifications by a trained gemmologist. Small inclusions neither mar its beauty nor endanger its durability.
Flawless - No internal or external flaws. Internally Flawless - No internal flaws. Very rare and beautiful diamonds which are quite expensive.
VVS1, VVS2 - Very, Very Slightly Included: Very difficult to see inclusions under 10x magnification. An excellent quality diamond.
VS1, VS2 - Very Slightly Included: Inclusions are typically not visible to the unaided eye. Less expensive than the VVS1 or VVS2 grades. Even properly graded VS2 diamonds can have visible inclusions in very large sizes or diamonds that do not have many facets which make flaws more visible such as an emerald shape.
SI1, SI2 - Slightly Included: Inclusions are typically visible under 10 x magnifications, SI clarity diamonds are usually of the best value since inclusions are not always visible to the naked eye and prices are reasonable when compared to prices of the VS2 clarity and up grades. Some SI clarity diamonds do have visible inclusions and should be evaluated carefully.
SI3 - Slightly Included-Included: SI3 is an EGL grade and is not recognized by GIA or other gemmological institutions. The SI3 clarity grade has been adopted by other labs as well. Typically an SI3 clarity grade would usually be given an I1 grade by the GIA.
I1 - Included: an I1 clarity diamond will have a visible flaw which can be seen with the naked eye, but there should only be one major flaw which is not too obvious. Overall the diamond should still look nice however I1 clarity grades vary quite a bit so one should be very careful when making a selection. If your budget only allows for an SI3 or I1 clarity diamond, be sure to examine it thoroughly before purchasing and make sure the inclusions do not detract from the overall beauty of the diamond.
I2, I3 - Included: These diamonds will have inclusions visible to the naked eye, and will have many black spots from the black inclusions and/or appear very cloudy or milky from the white inclusions, feathers and cracks.
Diamond colour grading scale
The diamond colour grading scale varies from totally colourless to light yellow. The differences between one diamond colour grade and another are very subtle and difficult to distinguish.
D-F: Colourless: perfect or almost perfect colour.
G-J: Near colourless: good to very good colour and this diamond may "face up" colourless when mounted into a setting, especially in white gold or platinum.
K-M: Light but noticeable yellow or brown tint.
Not recommended for larger diamond stone purchases, especially in engagement rings. Out of the 4 C's, colour and cut are the two most important characteristics of a diamond. Do not compromise on colour.
Diamond Cut
Many people confuse diamond cut with the shape of a diamond. Unlike shape, a diamond cut is the metric used to evaluate the precision and quality of the overall cutting itself. A diamond’s cut is the most complex of the 4 Cs, and not even the major labs agree on how to best measure the quality of a diamond’s cut. Diamond Cut usually takes into consideration 3 criteria: Proportions, Symmetry and Polish. Sometimes Light Performance or other tests can be used to also calculate the precision of the diamond cut.
When a diamond is cut to proper proportions, light is reflected from one facet to another and then dispersed through the top of the stone.
If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion (base of diamond). This will give minimal sparkle.
If the cut is too shallow, light escapes through the pavilion before it can be reflected. Making the stone look lifeless.
Up until several years ago, evaluating the cut of a diamond was not an easy task. Dimensions and proportions of the diamond as well as its finish (both symmetry and polish) were all the information able to be evaluated; thereby making it difficult for consumers to understand what is described as a well-cut diamond and what is not. Symmetry measures how well the facets match the other facets. A diamond cut with very good or excellent symmetry means that if you were to look at all the facets and compare to one another, they would look very uniform with very little variance. This doesn't mean however the diamond is not cut too deep or too shallow. Polish is a measure of the surface finish. If a diamond is only polished "Fair" or "Good" it does not allow maximum transition of light through the facets, due to its "rough" surface texture. Very Good polish by most lab standards is usually sufficient to get the top cut grade, and excellent/ideal is often preferred. Polish graded above Very Good is not detectable to the naked eye. So while symmetry and polish help you determine if the diamond is cut well, it doesn’t always mean the diamond will perform like a well cut diamond.
0 comments:
Post a Comment