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Glossary
A.
Aquamarine
Like emerald, aquamarine is a variety of beryl, a mineral that grows in crystalline formations. His typical shade, that varies from light blue to aqua green, is due to the presence of titanium or iron.
Aquamarine is a fairly widespread gem so it is not unusual to find even specimens of considerable size; moreover, thanks to its considerable hardness, it can being set in jewels with an oval, emerald or cabochon cut.
B.
Bezel
The bezel is the hollow element of the jewel in which the gem is embedded.
Brilliance
Is the amount of white light that the stone, in a “table facing up” position, is able to reflect in the eye of the beholder.
The refractive power of the diamond is unique; no other stone, in fact, reflects with the same intensity the light that hits it and crosses it.
Briliant
The brilliant cut is thus defined because it allows to maximize the brilliance of the diamond since all the 57 facets (plus a possible on the culet) of which it is composed, seem to radiate from the center of the stone towards its outer perimeter.
C.
Cabochon
“Cabochon” defines any type of cut without facets. The most common cabochon cut gives the gem a flat base and convex top.
Calipers
The calipers is the tool used in jewelry to measure the angles and dimensions of a diamond in millimeters or fractions of a millimeter.
Carat
Referred to the weight of the stones, “carat” means the unit of measurement of the mass (weight) of the diamond or other gems and is equivalent 0.2 grams. Etymologically, the term derives from the Greek kerátion (seed of carob tree). In fact, although it is a now debunked theory, in the past it was believed that the seeds of the carob had an exceptional constancy of weight and therefore that they could be taken as a reference for the evaluation of the mass of the gems.
Certificate
The gemologist reports that accompany the diamonds are draft to attest the natural or synthetic origin, the presence or absence of treatments and the characteristics of each stone.
The three main international certifications are issued by the Gemological Institute of America (GIA), the International Gemological Institute (IGI) and the Hoge Raad voor Diamant (HRD).
Clarity
Clarity represents the quality of a stone to be free from inclusions or defects. Depending on the grade, the classification system provides that it is labeled as IF-VVS1-VVS2-VS1-VS2-SI1-SI2-PIQUÈ.
The degree of clarity of a diamond represents, together with cut, color and carat, an essential feature for the attribution of value.
Claw
In jewelry, the term claw refers to one of the metal parts that contain a crown with which a precious stone is kept.
Cloud
A group of whitish inclusions, from extremely small to very small, which give the stone a cloudy appearance.
Color
The international classification system designates from the letter D the totally colorless diamonds up to the letter Z the slightly yellow ones.
In addition to cut, purity and carat, the quality of a diamond and its value is defined also by its clarity.
Crown
The term crown refers to that part of the diamond with a truncated-conical shape located above the girdle. It is made up of a larger facet (table) and a series of other underlying facets (side facets of the crown).
Culet
The culet of the diamond is the terminal part of the pavilion. When the stone has a faceted culet, it is known as the lower table.
Cut
All those operations that, starting from a rough stone, lead to the faceting, smoothing or carving it in order to intensify its brilliance.
It is from the early 1900s, that the cutting of a diamond – as well as symmetry and polish – constitutes an indispensable attribute to define its quality; namely when Marcel Tolkowsky, explained the diamond’s ideal cut proportions. According to the father of the brilliant cut, there are indeed ideal proportions of cutting to make the best use of the refraction and reflection of light entering a diamond for then going out ideally.
Cut proportions
The cut proportions (table percentages, crown height, girdle thickness, pavilion depht, total height) are shown as a percentage than the average girdle diameter.
It is generally agreed that the ideal proportions for the brilliant cut are the following: percentage of table diameter 58%; percentage of crown height 16.2%; percentage of pavilion height 43.1%.
D.
Diamond
Scientifically, a diamond is identified as the crystallized modification of a carbon atom with a specific gravity 3.52 and a hardness of 10 on the Mohs scale.
Dispersion
The term dispersion refers to the separation of light ray in the colors of the spectrum.
Drop (cut)
This particular cut shape follows the shape of a shining teardrop. It can be considered as a harmonious synthesis between the oval cut and the marquise cut.
E.
Emerald
As well as aquamarine, Emerald is a variety of beryl. Its typical intense and brilliant green tone is due to the presence of chromium and vanadium oxide: it is precisely the combination of these two elements that make the beryl an authentic emerald.
Most emeralds have evident inclusions, which means that this gem has a low degree of hardness and therefore scratch resistance.
Emerald (cut)
Is the square or rectangular cut with rounded corners. The cut is composed of three rows of facets parallel to the sides of the table and parallel to each other, in the crown, and by three rows of facets parallel to the sides of the girdle and parallel to each other, in the pavilion.
F.
Facet
The flat surfaces into which the outer part of the gem is divided after cutting.
Faceting
Cutting process of the facets of a gem.
Fancy color
Fancy color diamonds, ie diamonds that have a color saturation that goes beyond the letter Z of the GIA color scale, are classified in descending order based on their rarity, and therefore their value: red, green and blue, pink, orange and purple, brown and yellow, black.
Each color can be “Faint” (weak), “Light”, “Intense”, “Deep” and “Vivid” (marked).
Fancy shape
Any shape that is not a round cut.
Feather
In a diamond it refers to a fracture that resembles a feather.
Fluorescence
The fluorescence of a diamond is defined as the light that some diamonds emit when exposed to UV rays. It is rare that it is perceptible to the naked eye and therefore that it is so strong that it affects the aesthetic appearance of the stone. When this happens, the fluorescence of the diamond almost always takes on a blue color, and in very rare cases orange or yellow color.
On a descending scale, the light emitted by the diamond exposed to ultraviolet rays is classified as “None”, “Very slight”, “Slight” (weak), “Medium”, “Strong”, “Very strong”,. Diamond with no fluorescence are the most precious.
G.
Gemstone
A gemstone is a set of materials, most of them of mineral origin, but also distillates of molten rock and organic matter, used for ornamental purposes.
The preciousness, and therefore the value, of the gems is determined by their cut, their clarity, their color and their weight.
GIA
The Gemological Institute of America has more than 80 years of history and is among the most renowned research, certification and anti-counterfeiting institutes globally.
Recently, the Institute has developed an anti-sophistication device, capable of detecting synthetic diamonds with extreme precision.
Girdle
The girdle is the perimeter part of a cut diamond. It divedes the crown (the upper part of the stone) and the pavilion (the lower part of the stone).
Girdle thickness
The parameter that determines the thickness of the girdle is the average distance, in millimeters, between the crown (upper part of the stone) and the pavilion (lower part of the stone). However, this measure is generally expressed as a percentage.
H.
Hardness
The hardness, that is the ability of a mineral to resist scratching, is commonly measured according to the Mohs scale. This ordinal criterion of assigning the level of hardness requires that 10 minerals are numbered progressively according to their capacity to scratch the previous and be scratched from the next. The first mineral of the series is talc, followed by gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and finally diamond, the most resistant mineral in nature.
Heart cut
The heart cut, characterized by the presence of 59 facets, is not at all easy to achieve since it is only thanks to the skill of the craftsman that it is possible to obtain the maximum brilliance from the stone and give it correct proportions through such an irregular cut.
Hearts and arrows
The cut with hearts and arrows is a variant of the traditional round brilliant cut with 57 facets. This particular shape, characterized by eight symmetrical arrows in the crown and eight symmetrical hearts in the pavilion, is the result of a perfect combination of symmetry, brightness and a specific facet pattern.
Height
Measured in millimeters, the height of a diamond is defined as the distance between the table and the culet.
HRD Antwerp
The Hoge Raad voor Diamant is one of the most famous gemological Institutes in the world, and has its headquarters in Antwerp, the European capital of diamonds. The HRD certifications guarantee the authenticity of the diamond and describe in detail all its characteristics ( cut, color, purity, weight, proportions, fluorescence and level of polishing).
I.
Ideal cut
An ideal cut diamond is a round or princess brilliant cut diamond characterized by ideal proportions, as well as excellent polishing and symmetry values. An ideal cut diamond reflects almost all the light that penetrates it and, for this reason, it is one of the rarest cuts.
IGI
The International Gemological Institute is the oldest independent international Institute, based in Antwerp, for the classification and certification of diamonds.
Inclusion
Any internal characteristic or inhomogeneity of the gems visible with the microscope at 10 magnifications. Through these fractures or these the solid, liquid or gaseous particles found inside the gem it’s possible to distinguish between a natural stone from a synthetic one.
K.
Karat
Referred to the fineness of gold, “karat” – from the Arabic qīrāṭ (twenty-fourth part) – means the percentage of the golden part of a total of 24 parts of metal that make up the gold alloy. The gold of maximum purity, therefore, is indicated with the acronym 24 K (24/24 parts of gold).
Since pure gold is too “soft” to forge a jewel, in Italy goldsmiths use 18 K or 750 gold (on a 100 basis, 75% of the alloy is gold and 25% other metals). However, it is not unusual for diamonds to be fixed also with 14 K or 585 gold (on a basis of 100, the alloy is composed of 58.5% of gold and 41.5% of other metals).
L.
Laserscribe
The laser engraving technique allows to a thin and precise laser beam to inscribe the girdle of the diamond reporting the serial number of the Report.
M.
Manual loupe
It is a 10-magnification lens used to examine diamonds and gemstones.
Marquise
The marquise cut has an oval shape but with pointed ends; it is characterized by the presence of 56 facets.
The legend attributes the origin of this particular cut to the House of Bourbon. The story goes that the Roi Soleil had commissioned the cutting of a diamond that reminded the smile of the Madame de Pompadour.
O.
Oval
The oval cut gives the diamond an elongated oval shape. It is particularly suitable for women with small hands as this particular cut gives the stone the illusion of stretching the fingers.
P.
Parure
A series of two or more jewels made on the basis of aesthetic or functional complementary criteria. A set of diamonds, for example, is composed of a necklace, earrings and bracelet and ring of the same type.
Pavé
A type of setting in which numerous small diamonds are set next to each other so as to create a sort of “diamond encrustation” covering the entire jewel.
Pavilion
The term pavilion means the lower part of a diamond.
Percentage of height
Expressed as a percentage, it is the result of the following operations:
- for round brilliant diamonds: total height in mm/average diameter in mm.
- for fancy cut diamonds: total height in mm/smaller diameter in mm.
Percentage of the table
This parameter is obtained from the ratio between the diameter of the table and the average diameter of the stone.
Point
The centesimal fraction of the carat. So, for example, a ½ carat diamond will weigh 50 cents of a carat, or 0.50 carats (or 50 points).
Polish
It is referred to the condition of the outer surface of the cut diamond. The polishing is classified in a scale from “Excellent”, through “Very Good”, “Good”, and “Fair” to “Poor”.
Princess (cut)
A square or rectangular type of cut similar to the side of an inverted pyramid, with four beveled sides.
R.
Rhodium plating
This goldsmith technique give more brilliance to gold and silver and prevent oxidation, without alternating their physical properties. It is not invasive and lasts over time. After a thorough degreasing the precious metal, or the jewel, is covered by a galvanic bath of a thin layer of rhodium.
Ruby
Ruby is a noble variety of corundum, a mineral mainly composed of aluminum and chromium oxide. It is recognizable by its characteristic red color, which, in relation to the percentage of chromium oxide and saturation peculiar of each field, can take on very different nuances: from pale pink to deep and dark red, the so-called “pigeon blood” and from orange to purple.
S.
Sapphire
Sapphire is a precious gem, a variety of mineral corundum (such as ruby), made of aluminum oxide with traces of elements such as iron, titanium, chromium, copper or magnesium. It is typically blue, but it is not uncommon to find also “fantasy” sapphires in shades of yellow, purple, orange and green. The pink corundum can be classified as either a sapphire or a ruby.
Because of its remarkable hardness – it is the third hardest mineral after diamond and moissanite – sapphire is also used in non-ornamental applications such as infrared optical components or crystals for wristwatches.
Blue sapphires are listed according to the primary tone’s purity; purple, violet and green are the most common secondary colors.
So, the color of the best sapphires can therefore be described as a dark purple of medium intensity tending to violet blue where the main blue tone is at least 85% and the secondary one does not exceed 15%, without the slightest mixture of green or gray.
Setting
The term setting shows how to fix a gem on a frame.
Shape
The aesthetic configuration of a stone. The most common, although not the only ones, are the round, marquise, drop-shaped, heart-shaped, princess, radiant, emerald, cushion and triangle shapes.
Shining
Also called sparkling, is the effect produced by the flashes of light emitted by the facets of a diamond and visible as soon as this, or the light source, or the observer, move.
Sieve
Tool used to separate diamonds by size.
Symmetry
Is the classification of the overall uniformity of a stone’s cut. “Excellent” “Very good” “Good” “Fair” and “Poor” are the descending levels of definition.
T.
Table
Central facet of the diamond lying on a plane parallel to that of the girdle. Through the upper area, called the crown, it connects the girdle. The girdle is followed by a part below said pavilion that ends with a facet called the lower table or culet, parallel to the table.
Transparency
The quality of a stone to let light go through. A stone can therefore be transparent, translucent or opaque.
Triple excellent
A triple excellent diamond is a perfect diamond not only for cutting, but also for polishing and for symmetry. An evaluation of this type guarantees maximum brightness to the stone.