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Damascening
Process of inlaying of a soft metal (like
silver or copper) into a hard metal (like steel). The name has
coined from the name of city of Damascus, where this
process was introduced.
Demantoid garnet
A valuable green, very
lustrous granet with a cubic crystalline structure. These are a
rare variety of andradite.
Demi-parure
A demiparure is a matching set of jewelry,
usually containing a necklace, earrings, and a pin. See parure.
Diadem
A tiara, a circular or
semi-circular piece of jewelry that is worn on the head.
Diamante
Synonym of Rhinestone.
Diamond
Diamonds are very precious, lustrous gemstones
made of highly-compressed carbon and known for their shine and
value as well. They are one of the hardest
materials known. Diamonds have a hardness of 10, a specific
gravity of 3.5, and a refractive index of 2.417 – 2.419. They
comes in range of colors from colorless, to yellow, to orange, to brown, to
almost black. Some rare color of diamonds are red, blue, green, and purple.
A diamonds value is based on the “4 C’s”: color, cut, clarity,
and carat weight. The largest- known gem-quality diamonds
include the Cullinan (aka the Star of Africa, 530.20 carats), the
Excelsior, the Great Mogul (an ancient Indian diamond which is
said to have originally weighed 787.5 carats, but its location is
not known and nothing about it has been authenticated), the
Darya-i-Nur, the Koh-i-Nur, and the Hope diamond (named for its
purchaser, henry Thomas Hope).
Diapering
A crisscross pattern of diamond-shaped
lines on raised-dot enamel pattern.
Dichroism
Dichroism is the quality having more
than one color, especially when viewed from different angles.
Many minerals (like rubles and axinite) are naturally dichroic.
But this effect can be put artificially also by a thin layer of a
metallic oxides that is deposited on the surface of a material.
Die stamping
Known as
machine-stamping also it is a process in which sheet metal is cut and
shaped between two dies, forming a pattern in relief. Two steel
dies are used, the male die has the design in cameo, the female die has the design hollowed out. The male die is put
on top of the metal, the female die is put on the underside of
the metal. The press is forcefully brought down onto the dies and
metal, forcing the metal into the shape of the mold. Many
medallions and mass-produced jewelry findings are made this way.
Diffusion treated
A term used for stones whose color is enhanced
artificially. The diffusion process only colors
the outer surface of the stone, so chipping or repolishing will
result in a loss of color. Diffusion-treated stones are
already-cut stones that are heated in the presence of other
compounds (like iron oxide, chromium oxide, titanium dioxide,
etc.) that will infuse the extreme outer surface stone with
color. Diffusion treatment can also change the stone’s
refractive index.
Dog Collar
A short, multiple-strand choker-style necklace that fits
tightly against the neck. Dog collars are also known as “plaque
de cou” (meaning “neck badge”) when they are fastened by a clasp
in the front.
Doublet
Also spelled dublette it is a gem made from
two layers in order to save expenses. The lower part is
made of the
glass or a non-precious stone and the upper or top part has
more valuable stone. One common doublet contains a layer of real
garnet and a layer of glass.
Doubly refractive stone
It is a property of stone in
which the light
entering the stone is split into two light rays, and the rays
travel in different paths. The stones with such property
have more that one refractive index. Calcite, Peridot, zircon,
tourmaline, and tantalite are doubly – refractive stones.
Drop cut
A drop cut (or briolette) is a pear-shaped
cut gemstone with triangular facets on top. This type of stone
makes a nice pendant.
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