Diamond anatomy
Shape and cut
The round brilliant cut
The principal shapes of diamond.
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| Brilliant | Oval | Radian | Marquise | Heart | Emerald | Pear | Pincess | Triangle |
Proportions
Proportionscope:
The ideal cut
It is a very vast subject, which divides the professionals still today. To obtain the maximum of brightness, fire, � life �, a diamond must be cut according to certain dimensions and proportions. The diamond cutters must carefully consider the optical properties of each diamond to determine its optimal size.
Brilliance of a diamond following the proportions of its cut
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| Ideal cut: light is correctly reflected. Diamond has a beautiful brilliance and fire. | Too shallow: light is lost out the sides causing the diamond to lose brilliance. | Too deep: light escapes out the bottom causing the diamond to appear dark and dull. |
To obtain an ideal cut, the 3 principal elements, are:
1) Total depth %:
The height of the stone is divided by the diameter in rounds or by the width in all other shapes. Say the stone measures 6.52 - 6.56mm x 3.92mm, the total depth is 3.92mm � 6.54mm = 59.93%. Ideal round diamonds should have a depth of 59%-62.5%.
2) Table percentage (%):
Only round diamonds have a standard for table size. In round diamonds for a diamond to be recognized as an ideal cut the table must be relatively small. It must fall between 53% and 57%.
3) Girdle thickness:
The best girdle range for a diamond to fit in the ideal cut category for rounds is anywhere between � Thin � and � Slightly Thick �. The girdle could be Thin, Medium, Slightly thick or any combination of the three, such as � medium to slightly thick �. The various graduations thickness of the rondist are: Extremely thin, Very thin, Thin, Medium, Slightly thick, Thick, Very thick and Extremely thick.
4) Others :
Other elements are important, such as the culet size. The culet size is listed on a certificate and your diamond�s culet should be pointed (no culet), very small, small or medium because these are not visible to the naked eye. The graduations of the culet size are: No Culet, Pointed, Very Small, Small, Medium, Large, Very large and Extremely large. Avoid the culets equal or lower than � Large � which when you look at diamond by the table are very visible with the naked eye.
The girdle of diamond can be faceted, polished or rough. Diamonds which has a very beautiful cut have often the faceted girdle. A diamond cutter must work from additional time to facet it, which is not always economically profitable. A faceted girdle does not improve quality of diamond. The GIA evaluates only the . thickness of the girdle not the appearance.
Finish
Symmetry
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| Eccentric table | Eccentric culet | Deformed girdle |
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| Deformed facet | Misalignment of the crown and the pavilion | Undulated girdle |
Polish
The estimate of symmetry and polished results in
Fluorescence is a (normally) blue-white light effect that some diamonds exhibit. However, fluorescence can only occur in the presence of ultraviolet light (UV light). It is for this reason that UV light is used by diamond mining operations.
How Fluorescence Affects a Diamond
While fluorescence has no affect on the physical properties of the diamond, it can have an affect on the optical properties of a diamond. A diamond will receive a rating of "None" to "Very Strong" as far as the amount of fluorescence that can be seen in a given diamond. The level of fluorescence can change the perceived color of the diamond when it is viewed in normal lighting situations allowing for a slightly more yellowish diamond to appear white.
Most of us are familiar with UV lights, as they are popularly known as black lights". If you have ever been in a nightclub, then you will probably be familiar with seeing white clothing, and even teeth, glowing.
A diamond will be noted to have one of the following levels of fluorescence:
None (or Inert or Negligible)
Faint
Medium
Strong
Very Strong
Fluorescence does not have a huge impact on a diamond's optical properties, but can have a dramatic impact on its pricing. When looking through diamonds, it is important to check whether or not the diamond exhibits fluorescence. If it is indicated as having slight to medium, it should be of no concern. If the diamond has strong fluorescence it will be important to consult with a diamond specialist or view it for yourself, under different lighting conditions, and decide what effect you feel the fluorescence has. Less than 1% of the diamonds with fluorescence are affected in a negative way. If the diamond looks good to you, and more importantly, looks good to the person who will be wearing it,then the fluorescence is simply saving you money.
