| F-J | K-O
| P-T | U-Z
Setting | Bearding
Facet | Bezel
Setting | Brilliant
Spots | Certificate
Setting | Clarity
Setting | colour
Grading | colour
Angle | Crystal
| Cut |
Percentage | Diamond
Cutting | Diamond
Gauge | Dispersion
Reflection | Eye-Clean
a clarity characteristic that occurs on the surface of a diamond. Though some
blemishes are inherent to the original rough diamond, most are the result of the
environment the diamond has encountered since it was unearthed. (For more information
on the most commonly occurring types of blemishes, please see our detailed discussion,
Diamond Education: Clarity.)
the brightness that emanates from the very heart of a diamond. The brillance
factor makes diamonds unique among all other gemstones. While other gemstones
also display brilliance, none equals a diamond's light-reflecting power. Brilliance
is created primarily when light enters through the table, reaches the pavilion
facets, and is then reflected back out through the table, where the light is most
visible to your eye.
Setting: similar to a channel setting (see below). A bar setting uses a
thin, circular bar of metal to hold the stones in place on either side, so that
each bar has a stone on either side of it.
the term given to the very small feathers (small fractures that touch the diamond's
surface) along the edge of a diamond, usually appearing at the girdle, or widest
part, of the diamond.
Facet: the facet located on the crown, or top portion, of a diamond. Jewelers
call this the 'kite' facet because of its shape.
Setting: holds a diamond in place using a thin band of metal that surrounds
the diamond at its middle, or girdle. Bezel settings completely or partially surround
the stone, depending on the style and look desired, and provide good protection
for the middle and bottom (pavilion) portions of the diamond.
Cut: a type of round cut that gives the diamond 57 or 58 facets mathematically
devised to produce the greatest brilliance. 'Cut' here really refers more to the
diamond's shape than its proportions.
of a diamond's weight. A carat is equal to 200 milligrams. (Don't confuse this
Carat with the term 'Karat,' which is a measure of the purity of gold.) For accuracy,
diamonds should be weighed when they are not mounted in a setting. Each Carat
is divided into 100 parts called 'points,' so a 1-carat diamond has 100 points,
a ¾ carat has 75 points, etc.
Spots: misnomer used by some people in the jewelry industry to describe
the appearance of certain inclusions in a diamond. 'Carbon spots' are actually
included crystals that have a dark appearance, rather than a white or transparent
appearance, when viewed under a microscope. In most cases, these dark inclusions
are not visible to the naked eye and do not affect the brilliance of the diamond.
a guarantee by an independent laboratory that the diamond is indeed of the quality
the seller represents. Diamonds are certified by an independent gemological laboratory
with skilled gemologists who use specialized equipment to measure and evaluate
each diamond's particular characteristics and attributes.
Setting: a setting where two strips of metal (gold, platinum, etc.) hold
the diamond(s) in place at the sides. There is no metal between the stones. This
type of setting protects the girdle area of the diamond and secures small stones
more effectively than a prong setting. Channel-set diamonds also sit flush with
the mounting, making them less likely to get snagged on other objects, such as
hair or clothing.
measured by a jeweler's loupe (a small magnifying glass used to view gemstones)
under 10-power magnification. The FTC requires all diamond grading be done under
10-power magnification; any flaws not detected under this magnification are considered
to be non-existent.
the propensity of crystalline minerals, such as diamond, to split in one
or more directions either along or parallel to certain planes, when struck by
a blow. Diamond cutters use one of two processes--cleaving or sawing--to split
rough diamond crystals in preparation for the cutting process.
a grouping of a number of extremely tiny inclusions too small to be distinguishable
from one another, even under magnification. But under a microscope, this grouping
often looks like a soft transparent cloud inside the diamond. Clouds cannot be
seen with the naked eye, so usually do not significantly impact a diamond's clarity
grade. Diamond World will not sell any diamond with clouds severe enough to affect
the brilliance of the diamond.
Setting: several stones mounted together in a group, for a cluster effect.
Often several small stones surround a central, larger stone.
Grading: a system of grading diamond colours based on their colourlessness
(for white diamonds) or their spectral hue, depth of colour and purity of colour
(for fancy colour diamonds). For white diamonds, HRD
and IGI use a grading
system which runs from D (totally colourless) to Z (light yellow).
the most important thing to know is that, in general, the less colour a diamond
has, the more valuable it is, all other factors being equal. The less colour a
diamond has, the more purely it can refract the light that enters it, making it
sparkle with brilliance and fire. Diamond colours range from colourless to slightly
yellow or brown, to more rare and costly pink, green or blue stones (commonly
referred to as 'fancy' diamonds). Excluding 'fancy' diamonds, the ideal colour
for a diamond is colourless, although this is extremely rare.
the upper portion of a cut gemstone, which lies above the girdle. The crown
comprises the table, and the star- bezel- and upper-girdle facets. On round diamonds
and most fancy cuts, the crown consists of a table facet surrounded by either
star and bezel facets. On emerald cuts and other step cuts, the crown consists
of concentric rows of facets reaching from the table to the girdle.
Angle: a measurement of the angle, in degrees, formed by the facets of
the upper portion, or crown, of the stone. The distance from the girdle (widest
point) to the table (the flat facet at the top of the stone) determines whether
the crown will be thick, thin or proportionally 'ideal.' Therefore, the higher
the crown, the steeper the crown angle will be; the thinner the crown, the shallower
the crown angle will be. The angles at which the crown and pavilion facets (those
facets below the girdle) are cut directly affects the diamond's ability to refract
light rays, which is what gives a diamond its remarkable fire and brilliance.
a type of inclusion found in some diamonds. It is simply a mineral deposit
that has been trapped inside the diamond. Crystals are usually indicated on diamond
grading reports. Be aware that the location and size of the crystal may have a
direct bearing on the diamond's value.
the point on the bottom of a diamond's pavilion. On some diamonds, the culet is
actually formed into a facet; in others, it is formed into a point. Therefore,
round diamonds can have either 58 or 57 facets, depending on whether the culet
has been faceted or not.
the only one of the 4Cs that is within a human's control. 'Cut' refers to the
geometric proportions to which a diamond is crafted (usually by a master diamond
cutter with many years of experience). Once the diamond's shape has been determined,
facets are cut. These facets refract light like a prism and produce the stone's
fire and brilliance.
Depth: the height of a
diamond from the culet to the table. The depth is measured in millimeters.
Percentage: on a diamond grading report, there re two different measurements
of the diamond's depth:
1) the actual depth in millimeters (under 'measurements'
at the top of the report);
2) the depth percentage, which expresses how deep
the diamond is in comparison to how wide it is.
This depth percentage
of a diamond is important to its brilliance and value, but it only tells part
of the story. Where that depth lies is equally important to the diamond's beauty;
specifically, the pavilion should be just deep enough to allow light to 'bounce
around' inside the diamond and reflect out to the eye at the proper angle. Keep
in mind, also, that correct depth percentages vary based on the diamond's cut.
For example, a 75% or 78% depth in a princess cut diamond would be typical and
quite attractive. However, a depth of even 65% would be unnecessary and even detrimental
to a round diamond's beauty.
pure crystallized carbon, the simplest of all the gemstones. A diamond
begins to crystallize far beneath the earth's surface among a mixture of liquids,
gases, and crystals, called Kimberlite magma (after the city of Kimberley, South
Africa, where diamonds were found in the 1870's). Since Kimberlite is lighter
than surrounding rocks, it rises as gas from the earth's mantle, creating carrot-shaped
pipes through which diamonds reach the earth's surface. Diamonds can be from 1
to 3 billion years old-more than two-thirds the age of the Earth itself. Diamond
is also the hardest substance known to man. In fact, it can only be cut and polished
by another diamond. Despite its hardness, however, it is not indestructible. If
a diamond is struck at the right angle, it can chip or break.
Cutting: the method by which a rough diamond mined from the earth is shaped
into a finished, faceted stone.
First, the diamond often undergoes cleaving
or sawing to separate the rough into smaller, more workable pieces, which will
each eventually become an individual polished gem.
Next, bruting grinds away
the edges, providing the outline shape (for example, heart, oval or round) for
Faceting is next and is achieved in two steps:
1) during blocking,
the table, culet, bezel and pavilion main facets are cut; afterward,
star, upper girdle and lower girdle facets are added.
Once the fully faceted
diamond has been inspected and improved, it is boiled in hydrochloric and sulfuric
acids to remove dust and oil. The diamond is then considered a finished, polished
Gauge: an instrument used to measure a diamond's length, width and depth
arranged around the table facet on the crown are several smaller facets (bezel
and star facets) angled downward at varying degrees. These facets and their angles
have been skillfully designed to break up white light as it hits the surface,
separating it into its component spectral colours (for example, red, blue and green).
This rainbow effect, which appears as a play of small flashes of colour across
the surface of the diamond as it is tilted, is what we refer to as the diamond's
dispersion (also called 'fire'). This play of colour should not be confused with
a diamond's natural body colour (normally white, though sometimes yellow, brown,
pink or blue in the case of fancy colour diamonds). A diamond's natural body colour
is uniform throughout the entire diamond and is constant, regardless of whether
it is being tilted or not.
Emerald Cut: a square
or rectangular-shaped diamond with cut corners. On the crown, there are three
concentric rows of facets arranged around the table; and on the pavilion, there
are three concentric rows arranged around the culet. This type of cut is also
known as a Step Cut because its broad, flat planes resemble stair steps.
Reflection: finely polished diamonds should display a high degree of external
reflection. The finer the polish, the brighter and more lustrous the diamond will
be. External reflection should not be confused with internal refraction, which
refers to the primary light refraction that causes a diamond's fire and brilliance
to occur inside its facets. External reflection refers to the light rays that
are reflected back to the viewer's eye from the surface of the stone itself.
an expression that jewelers use to designate a gem whose flaws or inclusions cannot
be detected without a loupe.
on diamonds: A-E | F-J
| K-O | P-T