Dache, Lilly
Lilly Dache is the mark of Lilly Dache, Inc., a company located in New York and Paris. Lilly Dache produces high-quality hats, clothing, accessories, perfume, and cosmetics. The Lily Dache mark was first used on costume jewelry in 1923. Lilly Dache jewelry pieces are relatively rare and expensive. Lilly Dache was born in France, and began her fashion career there as a milliner (hat maker). She emigrated to New York, New York, USA, in 1924. Dache is reported to have said, "Glamour is what makes a man ask for your telephone number. But it also is what makes a woman ask for the name of your dressmaker." Dache's books include Lilly Dache's Glamour Book (published in 1956) and Talking through my hats (published in 1946).

Dalsheim
Dalsheim and "White Jet" are marks on costume jewelry made by Dalsheim Accessories, Inc. of New York, New York, USA. The company was founded by Maurice Dalsheim. These relatively rare marks were first used in 1939.

Damascening
Damascening is the inlaying of a soft metal (like silver or copper) into a hard metal (like steel). The name comes from the city of Damascus, where this process was first used.

Danburite
Danburite (Calcium borosilicate - CaB2Si2O8) is a clear to white silicate mineral whose orthorhombic crystals are transparent to translucent (danburite can also be yellow, greenish, or brown); it resemblestopaz. It was named for the city of Danbury in Fairfield County, Connecticut, USA (where the original specimens were found in 1839). Danburite is also found in Russell, New York (USA), Charcas and San Luis Potosi (Mexico), Kyushu Island (Japan), Madagascar, Siberia, Mogok (Myanmar), Bolivia, and Uri (Switzerland). Danburite has a hardness of 7 - 7.3 and a specific gravity of 2.97 - 3.02. Its streak is white.

Danecraft
Danecraft is a mark used on silver and vermeil (gold-plated silver) costume jewelry produced by Felch and Company, which was founded by Victor Primavera in 1938 in Providence, Rhode Island, USA. The company is now called Felch-Wehr (since 1977) and still produces silver and vermeil jewelry. Before the formation of Felch and Company, Victor and his brother Thomas had run the Primavera Brothers Jewelry Company in the 1930's, until Thomas' death. Primavera is a name now used by Danecraft for a line of its jewelry. Danecraft's Wingback earrings (from the 1950's) were a major product of the company. The piece above is a older Danecraft cat and dog pin.

Darya-i-Nur
Darya-i-Nur (meaning "Sea of Light") is one of the largest-known diamonds. It is a flawless, transparent, pink diamond from India, weighing about 175 to 195 carats. It was taken to Prrsia (now Iran) after Persia's attack on Delhi, India, in l739. The Darya-i-Nur is in the crown jewels of Iran, and was worn by the Shah of Iran.

Dead Pawn
Dead pawn is an item that was pawned but was never collected by the original owner.

"Dead" Stone
A "dead" stone is a foil-backed rhinestone that has lost its original shininess, usually after water has damaged the foil. For example, a "dead" clear rhinestone will appear dull and off-white, greenish or yellowish.

Dead Soft
Dead soft is a term that refers to very soft-tempered metal. Dead soft wire is the most easily bent wire. For example, copper electrical wire is dead soft.

Delft Jewelry
Jewelry made from Delft faience (tin-glazed earthenware) is usually set in silver, often with delicate filigree work and granulation. The classic hand-painted blue-on-white pottery often depicts windmills, flowers, and Dutch landscapes. Delftware jewelry includes necklaces, pendants, earrings, pins, bracelets, rings, charms, and cufflinks. Delft pottery has been in production in Holland since the middle 1600s, but Delft jewelry dates from much later. Delft blue is the most recognized Delft style, but other colors and styles have been used in Delft pottery and jewelry.

De Lizza & Elster
The De Lizza & Elster (D & E) company manufactured costume jewelry, buttons, and buckles; they sold wholesale to costume jewelry companies. De Lizza & Elster made pieces for Weiss, Kramer, Kenneth J. Lane, Hobe, Celebrity, Hattie Carnegie, Alice Caviness, Karu, and many others (including department stores). D & E was founded in New York, New York, by William De Lizza and Harold Elster around 1947. William De Lizza was the main designer. The pieces they made were not marked (only a paper hangtag indicated the brand). In 1967, D & E began making in-house pieces that they called "Juliana" -- these pieces were designed by Frank DeLizza (the co-founder William De Lizza's son) and were marked by a paper hangtag. Although D & E went out of business in the late 1990s, Frank DeLizza is producing copies of many of his popular original pieces.

Demantoid Garnets
Demantoid garnets are valuable green, very lustrous garnets with a cubic crystalline structure. They are a rare variety of andradite. Demantoid garnets have characteristic inclusions that look like horsetails. Demantoid garnets have a hardness of 6-7 and a specific gravity of 3.8 - 3.9. Demantoids were very popular in the 1800's, but are rarely used today.

Demilune
A demilune (meaning "half moon") stone is shaped like a half (or smaller) moon.

Demi-Parure
A demiparure is a matching set of jewelry, usually containing a necklace, earrings, and a pin. See parure. The demi-parure above is a set by Trifari.

Dendritic
Dendritic means tree-like, having a branching pattern (like moss agate).

Denim Lapis
Denim lapis is a relatively pale, inexpensive variety of lapis lazuli that is from Chile. It is the color of denim cloth due to calcite inclusions (which whiten the stone and lower its value).

Dentelle
Dentelles (meaning "lace" in French) are rhinestones cut with 32 or 64 facets.

DeRosa
DeRosa was a mark of the Ralph DeRosa Company of New York, New York. DeRosa produced very high-quality costume jewelry, including necklaces, earrings, bracelets, pins and fur clips, made from 1934 until 1970. Pieces were often made of Sterling silver, and had beautiful prong-set rhinestones, faux pearls, and/or excellent enamelling work.

Diadem
A diadem is a tiara, a circular or semi-circular piece of jewelry worn on the head.

Diamanté
Diamanté is another word for rhinestone.

Diamond
Diamonds are precious, lustrous gemstones made of highly-compressed carbon. Diamonds 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. Colors of diamonds range from colorless, yellow, orange, brown, to almost black. Rarer colors are red, blue, green, and purple; these colors (called fancies) are quite valuable. Canary diamonds have a deep yellow color. A diamond's value is based on the "4 C's": color, cut, clarity, and carat weight. A diamond's color (saturation) is rated on an alphabetical scale ranging from D (white) to Y (yellow). "Z" diamonds are fancy, or deep-colored diamond. A diamond's cut is designed to maximize the stone's natural "fire"; brilliant cuts are preferred. A diamond's clarity depends on the number and size of its flaws and inclusions (of other minerals, like quartz). Clarity is rated from FI (flawless), IF (flawless at 10x magnification), a series of V ratings (very small flaws at 10x magnification), a series of S ratings (small flaws at 10x magnification), to I1, I2, and I3 (having inclusions visible to the naked eye). A diamond's carat weight is simple how much it weighs (a carat is about 0.2 grams or about 0.007 ounces). 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 not known and nothing about it has been authenticaed), the Darya-i-Nur, the Koh-i-Nur, and the Hope diamond (named for a purchaser, Henry Thomas Hope).

Diapering
Diapering is a crisscross pattern of diamond-shaped lines on a raised-dot enamel pattern.

Dichroic Glass
A glass which contains ultra-thin layers of aluminum, chromium, silicon, zirconium or the metal alloy titanium. The colors are almost holographic in appearance.
Addition of the various elements is what produces the bold and dramatic colors. Colloidal gold may also be added. The appearance will be different depending on whether the light is reflected or transmitted.

Dichroism
Dichroism is the property of having more than one color, especially when viewed from different angles. Many minerals (like rubies and axinite) are naturally dichroic. This effect can be artificially caused by a thin layer of a metallic oxides that is deposited on the surface of a material. Dichroic coated glass transmits some wavelengths of light and reflecting others, giving it an opal-like appearance.

Die Stamping
Die stamping (also known as machine-stamping) 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 (protruding); 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
Diffusion is the process of color enhancing a stone by heating the stone in the presence of iron oxide, chrome oxide or similar compounds. The process colors the stone by infusing the outside surface of the stone with color. Only applied to cut stones as any further cutting would remove the color enhancement. This process is often used on sapphires and topaz to heighten or alter the colors.

Diffusion Treated
Diffusion treated stones are color-enhanced (not naturally colored) stones. 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. Under a microscope, you you can see the loss of color within each tiny scratch. Diffusion treatment can also change the stone's refractive index. Also, if the stone is faceted, the color will appear stonger where the facets meet.

Dinosaur Bone
Petrified Dinosaur Bone or"dino bone" is the result of fossilized bone from dinosaurs in which the cellular structure has been replaced with quartz, leaving the bone structure intact.

Dior
Christian Dior (1905-1957) was an influential French fashion designer. In the 1950's, Dior jewelry was produced by Kramer (in the 1950's), Henkel & Grosse (from 1955) and Mitchel Maer (from 1952-1956). In 1955, Swarovski and Christian Dior developed the iridescent aurora borealis stone Licensed Dior jewelry continues to be produced.

Dog Collar
A dog collar (also known as "collier de chien") is a type of 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. Dog collars are 14"-15" in length.

Dog Tag Jewelry
Dogtag jewelry is based on the dogtags issued to soldiers. This type of necklace has become popular recently. Dogtag necklaces consist of a flat, dogtag-shaped pendant strung on a silver ball chain.

Dolomite
Dolomite (calcium magnesium carbonate, CaMgCO3) is a common type of sedimentary rock. Dolomite occurs in crystals and in masses. This mineral was named for the French mineralogist Déodat de Dolomieu (1750-1801), who first described it in 1791.

Domed
A convex shape like the outside surface of a ball or sphere. This shape is often used in earrings, pendants and components of jewelry designs.

Doublet
A doublet (also dublette) is a gem made from two layers in order to save expenses; the lower part of the composite stone is glass or a non-precious stone, the top is the more valuable stone. Many different types of doublets have been manufactured (including opal doublets). One common doublet contains a layer of real garnet and a layer of glass. A thin, red garnet top is glued to a colored glass bottom. A green glass bottom with a red garnet top layer produces an emerald-like stone. A diamond is enlarged by cementing it to a crystal base.

Doubly Refractive Stone
In doubly-refractive stones, lthe light entering the stone is split into two light rays, and the rays travel in different paths. These stones have more than one refractive index. Calcite, peridot, zircon, tourmaline, and titanite are doubly-refractive stones. Bi-refringence is another name for double refraction.

Drawn Bead
Drawn beads are cut from a long, straw-like tube of glass (the tube is made by drawing a hot mass of glass fresh from the furnace). The sharp-edged cut beads are often tumbled and reheated to give them rounded edges. Some examples of drawn beads include seed beads, bugle beads, furnace glass beads, and pony beads.

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.

Drusy
Drusy (sometimes referred to as: druse, druzy) is a layer of tiny quartz crystals that form on a host stone. The cavity inside a geode is sometimes filled with drusy quartz crystals. Although the quartz crystals may be the source of the color (amethyst, citrine), usually it is the host stone's color (chrysocolla, uvarovite garnet) that shows through the quartz and gives the stone its color. (pronounced: dru-zee)

Druze
Druze is a layer of crystals that form within a mineral crust, like the inner cavity of a geode. Amethyst crystals are often found in a druze. The inner cavity of agate geodes are often lined with a druze of sparkling quartz crystals.

Ductile
A ductile substance is easily pulled or stretched into a thin wire. gold is the most ductile metal.

Duettes
Duettes are sets of jewelry made by the Coro, Trifari, and other companies. Each "duette" has two clips which attach to a pin base; they can be worn as a single pin or as two clips. The enameled bird duettes above were made by the Coro company

Du Jay
Du Jay was a small costume jewelry company that made high quality (and high priced) pieces during the middle 20th century. Rhinestones and/or false pearls often adorned the lockets, pins, bracelets, necklaces, and other jewelry items which were often made of silver (sometimes with a gold wash). Du Jay items are hard to find.

Dull
The term used to describe gems which exhibit an earthy or dull luster, meaning their surface does not reflect light very well. Plastic can be described as having a dull luster as is clay. Hematite that does not have a highly polished surface will display a dull luster.

Dumortierite
Dumortierite (Aluminum Boro-silicate Hydroxide) is a blue to violet silicate mineral that is used as an ornamental stone (and sometimes as a semi-precious stone in jewelry). Dumortierite quartz is a massive variety of opaque quartz that is intergrown with dumortierite crystals. Dumortierite has a hardness of 7 - 8.5 and a specific gravity of 3.3 - 3.4.

DWT.
A measure of Troy weight, dwt. is the abbreviation for "pennyweight", a measure used to weigh gold, silver, and jewels. In Troy weight, the pound = 12 ounces, the ounce = 20 pennyweights, and the pennyweight = 24 grains. While this method of weighing is believed to have originated in Cairo during the crusades, the name comes from Troyes, France where it was first used .