It is a scale to measure the hardness of a mineral. It is used by
scientists as it has its numbers in proportion. Mineral collectors
measure hardness using the Mohs scale.
It is the absorbed light in a gem or mineral when bands of light passes
through. Different gems have different absorption spectra. All are
unique about which colors are absorbed and which pass through. This
plays a major role in identifying gems and it is easily distinguished
between an imitation gem to the real thing. To determine the absorption
spectra of a mineral, a spectroscope is used.
It is an aggregate of long, slender, crystals i.e. Natrolite. The term
is also used for the crystal habit of a single long, thin, slender
It is a type of chalcedony which is found in many different patterns
and colors, often with varying color layers.
It is a term given to the grouping of crystals. It is defined by the
way crystals are clustered together.
It is a crystallized and transparent quartz, found typically in violet
or purple. It is the birthstone for the month of February.
It is a semiprecious blue colored stone from the beryl family. It is
the birth stone for the month of March.
A look alike gem material which is either a manmade imitation or a
It is a rectangular style of a step cut and used for small gem
It is a term used for irregular in shape, like baroque pearls,
tumble-polished stones, or freedom shaped gem materials.
It is a small stone which has been cut into a sphere shape.
It is a lightly colored mineral, called emerald when transparent and
dark green and known as aquamarine if the color is blue.
Each month of the year has a particular gemstone associated to it. They
are as follows:
January - Garnet
February - Amethyst
March - Aquamarine
April - Diamond
May - Emerald
June - Pearl, Alexandrite
July - Ruby
August - Peridot
September - Sapphire
October - Opal, Rose
November - Yellow Topaz, Citrine
December - Blue Topaz
It is a term used to any surface imperfection on the surface of a
gemstone. As for example of a diamond, one would be referring to a nick,
knot, scratch, abrasion, minor crack or fissure (cavity), or a poor
For many years, this term was used in trading of a diamond without its
distinctive body color. Now, according to the Federal Trade Commission,
diamonds with a distinct blue body color will be trades as "blue-white."
It is a synthetic gem which is created from molten liquids placed in a
tear shaped molds to crystallize, leaving them with a tear-like form. It
is mostly applied for synthetic Rubies and Sapphires.
It is the term used for the total amount of white light returned to the
eye from a diamond or any colored stone as the result of internal and
external reflections. The factors which affect the amount of brilliancy
in a gem are the refractive index, proportions, polish and transparency.
It is the most common style of diamond and many other gemstones cutting
that consists of a combination of triangular and kite shaped facets.
There are 57 or 58 facets in a round brilliant cut.
It is an unfaceted cut stone of a domed form, having a convex surfact.
It is often also called as "cab."
It is a carved gem or shell where the outer layers are cut away in such
a way that the design stands out in relief against a background of a
It is a term which refers to diamonds with an intense yellow hue. If
the yellow make the stone very distinctive, then the term "fancy
yellow" is also often used.
The aggregate which is composed of tiny, thin, straight, long crystal
strands; hairlike. Example: Millerite.
It is a unit of metric measurement used for gems. It is abbreviated
with 'ct.' One carat is equal to 100 points, 200 milligrams, 1/5 of a
It is a black-appearing inclusions in diamonds, which is caused by the
addition of graphite or homblende minerals.
It is a group of minerals which contain one or more metallic elements
along with the carbonate radical (CO3
). Most of them are
lightly colored and transparent in pure form. All the carbonates are
soft, brittle, and effervesce when they are exposed to warm hydrochloric
acid. The carbonates are divided as Calcite group, Aragonite group.
Sometimes, the Nitrates and Borates are also considered as a category of
It is form of penetration twinning where the two Orthoclase crystals
form interpenetrating twins.
Two crystals which twin in a repeated pattern. It is also known as "repeated
of color (color change)
It is a phenomenon, only in some colored stones, where the gem material
appears in different color in different types of light. This is usually
caused by selective absorption and/or transmission of specific type of
light to which the gemstone is exposed.
It is a term which refers to the various types of colored stone,
including milky, carnelian, agate, cat's eye and also jasper.
It is a form of contact twinning where six Chrysoberyl crystals join at
the base to form a six-pointed formation.
It is a brownish-orange quartz variety. It is the birthstone for the
month of November.
It is also sometimes called "fracture filled." It is a term
used for a gemstone which has been treated for the improvement of its
appearance by filling fissures or fractures with a transparent
Diamonds are ranked on a scale from flawless, which is no inclusions
visible under 10x magnification, to included i.e. eye visible
inclusions. Clarity grade is one of the such four value factors.
It is the tendency of a crystalline mineral to break in a certain
definite directions called cleavage planes. The breakage of such
cleavage is done by cleaving. Cleaving is a process where a stone is
studied in order to define the plane and divide it with a swift blow.
The swift blow splits the stone into proportions quickly as opposed to
It is a name given to all natural gemstones, leaving diamonds or
Diamonds are ranked on a scale from "D" to "Z." "D"
for colorless and "Z" for noticeable tint of color, typically
yellow or brown. Diamonds with saturation greater than "Z"
color are considered to be Fancy Colored Diamonds and are graded on a
separate scale. Color grade is referred to one of the four value factors
of the diamond.
It is a term used for the determination of the cause of color in fancy
colored diamonds. Diamonds which are naturally colored are very rare and
expensive. The two common ways that enhance the color of diamonds are
irradiation and the high pressure and high temperature (HPHT) process.
It is a crystallized aluminum and oxygen gem mineral. The most valuable
type of corundum are ruby and sapphire.
It is the part of any faceted gemstone above the girdle.
It is the small facet polished across a stone, otherwise it would have
been a sharp point or tip of the pavilion of a faceted stone, especially
a round brilliant cut. The main purpose of this cut is to avoid breakage
of this tip.
It is a pearl which is being produced by implanting a shell bead or
mantle tissue into the body of a pearl which bears mollusk. The leading
cultured pearl producing countries in the world are Japan, China,
Tahiti, Australia, the U.S., and the Persian Gulf.
It is a mineral which crystallizes in the cubic system and is composed
of carbon with a hardness of 10 on Mohs scale. Its refractive index is
2.417 and specific gravity, 3.52.
It is a term used for the separation of white light into its component
spectral colors. (also see fire).
It is a term given to the phenomenon which is exhibited on all
non-opaque minerals, leaving amorphous ones and those that crystallize
in the isometric system. When a ray of light enters the crystal, it
splits up into two separate rays and makes everything observed through
the crystal appear as double. In many minerals it is very weak and is
observed only through special instruments but in some minerals like
Iceland Spar variety of Calcite is strongly visible. Double refraction
differs from mineral to mineral. This property is used in identifying
gems. It is measured with a refractometer.
There are many gem fakes, one of them is this. In it a thin, flat
section of a real gem is pasted atop a thick base of glass or rock
It is a term for exhibiting a pinched crystal figure on both bases.
It is a combination of hardness, toughness and stability which
describes the specific gemstone's ability to resist wear.
It is the green colored beryl and among gemstone it is one of the most
valuable one. It is the birthstone for the month of May.
It is a style of cutting a gemstone where the outline is of rectangular
shape with cut corners and the shape of the facets are rectangular and
It is a term used to carve letters or image out of a gemstone.
It is a process in which rocks are worn away from natural procedures,
like water and wind.
It is a term for an individual flat section of a faceted gem.
It is one of the small and flat surfaces of a gemstone which is
polished to increase its brilliancy and beauty. A round brilliant cut
gemstone has a total of 57 or 58 facets.
It is the gem of plane faces or facets.
It is a girdle of a stone which is lapped and polished for its maximum
surface reflection. It has many flat planes around the circumference of
It is a fracture or break in a gemstone which is typically white and
feathery in appearance.
It is a term which refers to the quality of fashioning a gemstone,
including the polish and symmetry.
It is the flashes of spectral colors which are seen in a gemstone as a
result of dispersion.
It is an inclusion or a crack in gemstones which generally demotes its
It is the process of a material which emits visible light when it is
subject to ultraviolet light. As an example, diamonds under UV light
often emits a visible light of a blue hue.
It is cut, color, clarity, and carat weight. This phrase is used to
describe a diamond's value characteristics.
It is a break within a gemstone.
It is term given to a pearl which forms in a freshwater living mollusk.
It is a description of a brilliant cut, a round stone with 57 to 58
It is a semi-precious stone and a family of crystal, generally in
reddish-brown color but even ranges from true red to violet or blackish
red. The name has been derived from its resemblance to red pomegranate
seeds. The red garnet is the birthstone for the month of January.
It is a sandpaper which is composed of tiny, hard, garnet crystals,
glued on it for the use of an abrasive.
It is a precious or semi-precious stone that is cut and polished for
the use in jewelry.
It is the science and procedures being involved in mining, faceting,
and also marketing of gemstones.
It is a term for an individual who is practicing in the subject of
It is a smooth and round growth formed within the mollusk shell due to
an irritant. It is used as gem.
It is the narrow band around the widest part of a polished or faceted
gemstone, which divides the crown and pavilion facets.
It is the attributes of crystal's or aggregate's appearance.
It is the ability of a gem to resist scratching.
It is in reference to a mineral or a gem which is put under intense
heat to enhance color or remove flaws.
It is in reference of a doubly terminated crystal which has two
differently shaped ends.
It is a term for polyhedron with six sides and a top and bottom base.
It is for any of the mineral that has four axes out of which three are
equal in length and lie at an angle of 120° from each other. The
fourth one may be long or short but at right angle toward the other
It is a surface which has been polished to a mirror-like finish.
It is a form of crystal which exhibits an indenting, terraced,
structure penetrating towards the center.
It is the primary impression of color like red, green or blue.
It is the internal characteristics present in gemstones. The common
inclusions in diamond includes feathers, crystals, fractures, graining,
pinpoints, cavities, etc.
It is a mineral which is used as a gemstone. It occurs in deep blue,
purple, light blue-gray, and yellow-white.
It is the prismatic colors inside or on the surface of a material which
is caused by light interference from thin layers of differing refractive
indices. The layers may be thin films of liquid, gas or solid. Pearls
are best known for their exhibiting iridescence.
It is a type of contact twinning where two single quartz crystals are
joined from their base at an angle near 90°.
It is a term used for an individual who facets gemstones as a trade.
The shop of such individual is also called such. It is even sometimes
used in adjective form relating to gems, like lapidary equipment.
It is a small magnifying lens which is used to observe certain aspects
of gemstone. It commonly have a magnification level of 10x.
It is the quality of the reflected and refracted light from the surface
of a gemstone or pearl.
It is a term for having large crystals which can be easily seen with a
It is a term used for describing the dark colored rocks or minerals
which is composed of magnesium and iron.
It is the trade term which refers to the proportions, symmetry, and
polish of a gemstone.
It is a term used for the fashioning style for gemstones which has the
girdle outline in an elliptical shape with pointed ends.
It is a material which has an embedded crystal inside or emerging from
It is a term which refers to a non-shiny, frosted surface.
It is a term used generally to describe small, round faceted diamonds
or the colored stones of approximately 0.18 carat or less.
It is a loose scale of hardness devised by a German mineralogist,
Friedrich Mohs in the 19th century. It is used for field collecting,
which allows for identification of specimens. The comparative scale of
hardness is as follows:
8) topaz and beryl
It is a family of marine creatures having soft fleshy body surrounded
by a calcareous shell. It includes the oyster and snail.
It is a translucent stone which is often bluish in color, yet sometimes
It is a term for the iridescent inside of a mollusk shell that is used
as an ornament. It is different from pearl.
It is a trade term for particular portion of a piece of jewellery in
which a gem or other object is set.
It is term for exhibiting two or more of colors on a single specimen.
It is the secretion of iridescent substance by a mollusk during the
formation of a pearl. It consists of layers of aragonite and calcite
It is a trade term for a particular portion of the original surface of
a rough diamond left by the cutter while polishing and faceting a
diamond. Naturals are generally found near the girdle of a diamond and
are represented in green on a plotting diagram.
It is a name given to a pearl which originates naturally in a mollusk.
It is distinguished from cultured or imitation pearls.
It is a minor chip on the surface of a diamond which is generally found
near or on the girdle of the stone.
It is a semi-precious stone which is composed of chalcedony and is
found naturally in white or gray. The white variety of the onyx is
generally dyed black.
It is a non-crystalline, iridescent silica. It is the birthstone for
the month of October.
It is term which refers to the transparency of a gemstone. Opaque
materials do not transmit light.
It is the soft iridescent glow on or just below the surface of a pearl
or cultured pearl. Orient is caused due to the interference and
diffraction of light from the minute crystals comprising the pearl's
It is a fashioning style for gemstones which has the girdle outline in
an elliptical or oval shape.
It is a style of setting of small stones to the maximum possible
closeness in two or more rows.
It is that portion of a faceted diamond or any other gem material which
lies below the girdle.
It is the fashioning style fo gemstones with the girdle outline in the
shape of a tear drop or pear.
It is a transparent gem which is olive green in color. It is the
birthstone for the month of August.
It is a schematic diagram included on the EGL USA Diamond Certificate.
It illustrates the facets, printed in black, of a diamond and the
approximate location and type of internal and external characteristics,
printed in red and green.
It is a measurement in the weight of a diamond. One point is equal to
1/100 of a carat. Hence, 0.50 carats is equal to 50 points.
It is the smoothness of the surface of a fashioned gem. On it the
optical reflection is maximized and it shows no visible wheel or burn
It is a girdle which has been lapped or polished to yield a uniform and
a highly reflective surface.
It is rare and costly gems like diamonds, emeralds, sapphires, and
It is a modification of a brilliant square-cut gemstone. It is
generally square-shaped in diamonds.
It is a crystalline mineral which is used for gems, including amethyst
and rock crystals. It is available in variety of colors.
It is a type of cut which is usually found in diamonds.
It is the return of light after striking the surface of stone.
It is the change in the direction of a ray of light which enters a
It is a variety of garnet which ranges from rose-red to pale violet.
It is any of the uncut or unpolished gem material.
It is a precious stone which is highly valued. The most common color of
the stone is red. Red colored ruby is the birthstone for the month of
It is a precious stone from the family of corundum. It is highly valued
and the most common color seen is blue. The blue colored sapphire is the
birth stone for the month of September.
It is a matte finish which is made by sandblasting, brushing with a
stiff wire brush or then by chemically altering a high shine surface.
Satin finish has a soft, pearl-like luster instead of bright polish.
It is a mirror-like reflections from the facets of a gemstone as it
turns in the light.
Any stone which is suitable for use in jewelry but is not a diamond,
ruby, sapphire, or emerald. Few examples of semi-precious stones are
amethyst, aventurine, carnelian, garnet, opal, and rose quartzes.
Semi-precious stones are quite costly.
It is any substance which is fashioned to imitate the appearance of a
It is a brilliant round cut which has 17 or 18 facets: 8 bezel, 8
pavilions, a table and a culet facet.
It is the quartz which are brownish in color, with a smoky appearance.
It is a term used to refer to a ring containing a single diamond or any
It is the eight triangular facets which surround the table facet of a
round and brilliant cut diamond.
It is a type of gem cut with a varying number of sloping parallel rows
of four-sided facets which give the impression of harder.
It is a term used to refer to the quality of the fashioning of a
gemstone. In symmetry grade the consideration is the balance of the
outline shape and the precision of the facet arrangement.
It is a man made gem material with same physical, optical and chemical
properties as that of its natural counterpart.It is a man made gem
material with same physical, optical and chemical properties as that of
its natural counterpart.
It is the horizontal and top flat facet on the crown of a faceted
gemstone. The percentage of the table is a comparison of the table facet
size to that of the width of the stone at the girdle.
It is an attribute of color which determines its lightness or darkness
It is a transparent gem. Wine-yellow colored topaz is the most precious
one. Other colors which exists in topaz are white, blue, brown, orange,
and pink. Blue colored topaz is the birthstone for the month of
It is the breakage (fracturing) resistance ability of a mineral or
gemstone. The toughness is different from the hardness of a stone.
It is a crystalline mineral that is used as a gemstone. It comes in
variety of colors but the most common of them are pink and green.
It is the ability of a substance to transmit light.
It is a general term used in describing gemstones which have been
artificially modified to improve their color or clarity. The techniques
which are included are laser drilling, fracture filling (clarity
enhancement), high pressure high temperature (HPHT) annealing,
irradiation and surface coloration. The gemological laboratories have
the equipment and experience to detect more difficult treatments.
It is a term used for a triangular shaped and faceted gemstone. To be
more specific, the term is used for a gemstone that has an arched shaped
triangle cut with 25 facets of the crown and 19 facets on the pavilion.
It is the two or more mineral crystals which have been grown together
in a symmetrical nature, generally non-parallel. It is sometimes also
known as twinned crystals.
It is a weight unit practiced in England and the U.S. for precious
metals. 20 pennyweights (dwt) is equal to one troy ounce, and 12 troy
ounces is equal to one troy pound.
It is the light that is invisible to the naked eye as it consists of
shorter wavelengths than those of visible light.