Brilliance is what makes a diamond sparkle. When white light shines on the diamond, a luminescent reflection is seen. A correctly cut diamond increases the reflection of the light and has a maximal brilliance.
A round diamond with 57 facets that are arranged in a certain way, has an optimal brilliance and light reflection.
A diamonds weight is expressed in carat, one carat being an equivalent of 200mg. Evidently, the heavier the diamond, the more expensive. The word carat is derived from carob. In ancient India gems were weighed with carob beans that all weighed exactly the same.
A diamond is given a grade to describe the level of inclusions or imperfections. The less imperfections, the better the clarity.
FL = Flawless. There are no internal or external inclusions visible under a x10 magnifying glass to the trained eye. This is the best and most expensive clarity grade.
IF = Internally Flawless. There are no internal inclusions visible under a x10 magnifying glass to the trained eye. There is a minor external imperfection in the finish.
VVS-1 = Very Very Small inclusion 1. Usually just one tiny inclusion, visible under a x10 magnifying glass to the trained eye.
VVS-2 = Very Very Small inclusion 2. Tiny inclusions, only visible under a x10 magnifying glass to the trained eye.
VS-1 = Very Small Inclusion 1. Very small inclusions, visible with a x10 magnifying glass.
VS-2 = Very Small Inclusion 2. Very small inclusions, visible with a x10 magnifying glass.
SI-1 = Small Inclusions 1. Small inclusions, visible with a x10 magnifying glass.
SI-2 = Small Inclusions 2. Several small inclusions, visible with a x10 magnifying glass.
SI-3 = Small Inclusions 3. Inclusions that may be visible to a trained observers naked eye.
I-1 = Included 1. Flaws that are visible to the naked eye.
I-2 = Included 2. Many flaws that are clearly visible to the naked eye and that have an effect on the brilliance.
I-3 = Included 3. Many flaws, clearly visible to the naked eye. The brilliance is decreased and the structure of the diamond is compromised: it can break or chip easily.
A cluster of very small internal inclusions. Tiny clouds will not interfere with the stones brilliance, but a cluster of clouds will.
A diamond must be as colourless as possible. The colour grade describes the colour tones in a stone. D is perfectly colourless, which is rare and expensive. The colour scale goes from D to Z and indicates yellow and brown tones. It takes a trained eye to distinguish between shades that are close together, but an untrained eye see the difference between shades that are several tones apart with a little practice. Pink, blue, red, and green diamonds are also found, but they are very rare and expensive. These fancy coloured diamonds don’t follow the normal colour/price scale and are priced separately.
D= exceptionally white
E= exceptionally white
F= rare white
G= rare white
I-J= slightly tinted white
K= tinted white
M, N-O, P, S-Z= tinted colour
A culet is the bottom facet of a diamond. It is best to have a small or medium sized culet. A large culet will let the light escape, instead of reflecting it. When there is no culet, the bottom of the stone will chip easily.
Commonly used to refer to both the shape of a stone (round, pear, oval, etc.) and the make (the exact geometric proportions to which a diamond is cut). The make of a stone is the most important factor in determining how much sparkle comes from a diamond, regardless of the shape.
When a round diamond is cut to perfect proportions, its depth and table percentages are perfectly balanced. The ideally cut stone also has the best grades on polish and symmetry, which can only be reached when the stone is fashioned with great care. The beauty of the stone is enhanced by the finest craftsmanship.
Very Good Cut:
A diamond with a very good cut has very strict requirements for depth and table percentages. These proportions give the stone a maximal brilliance and icy fire.
A diamond with a good cut has acceptable but imperfect proportions. Its brilliance and fire is good, which makes it a good stone for jewellery.
A diamond with a fair cut has less than perfect proportions to make the most of the weight. This cut sacrifices the brilliance of the stone.
A poorly cut diamond has imperfect proportions that make it look lustreless. Diamonds with a poor cut are not recommended for fine jewellery.
The depth of a diamond is measured from the culet at the bottom, to the table facet at the top.
The depth percentage is the height of the diamond (measured from the culet to the table) divided by the width. The depth is crucial for an optimal brilliance and fire. When the depth percentage is too low, the diamond will loose its sparkle because the light is leaking out.
An eye-clean diamond is flawless to the naked eye, meaning it has no visible inclusions. Diamonds with a SI-1 grade or better are usually eye-clean.
Facets are the flat, polished surfaces on a diamond.
A diamonds fire, also called refraction or dispersion – is the coloured light that is reflected from within. When white light enters the stone, it is broken down into all the colours of the rainbow, because the diamond acts like a prism. Only a diamond with perfect proportions can have good fire.
Certain diamonds disperse a bluish glow when exposed to ultraviolet light. A diamond should not have strong fluorescence, but faint or moderate fluorescence does not affect the diamonds look. Some customers prefer a faint fluorescence, because it balances the yellow colour of some of the less expensive stones.
The girdle is the narrow band around the diamonds outer circumference. It is usually the place where the setting holds the diamond. The girdle can be rough or polished, but either is good because it doesn’t affect the overall beauty of the stone.
Inclusions are internal imperfections in a diamond, such as a spot or irregularity. Irregularities can include a fracture, a smaller diamond inside the bigger one, included liquid etc. In SI-3 clarity diamonds (or lower quality) the inclusions can be seen with the naked eye. In higher quality stones the inclusions are only visible under magnification. The fewer the inclusions, the better the clarity grade, the rarer the stone and the higher the price.
A diamonds make is the quality if its finish and proportions. A good make will enhance a stones brilliance and fire. A poor make will decrease the stones sparkle and fire.
The pavilion is the bottom half of the diamond, from the lower girdle to the culet. If the pavilion is too deep or not deep enough, light will leak out of the diamond and it will loose fire and brilliance.
A point is a means to express the weight of a diamond. One point is 1/100th carat. A diamond that weighs 0.50 carat weighs 50 points.
A diamond is given a grade for its finish, from poor to excellent. The polish is very important, because a good polish can enhance the stones fire and brilliance. It takes a trained eye to differentiate between the different grades.
Sparkle or scintillation is the amount of light that is reflected from the diamond as it moves. It is the combination of fire and brilliance.
A diamond is given a symmetry grade for its overall cut uniformity. The symmetry grade can go from poor to excellent. Poor symmetry will decrease a diamonds sparkle and fire, because the light is leaking from the stone.
A diamonds table is its top facet. If the table is too small or large, this will influence the overall proportions, brilliance and fire.
A diamonds table width % is the width of the table, divided by its total diameter. It is a crucial parameter for a diamonds sparkle.