Damascening: Designs made of gold, silver, or copper decorating a base metal.

Danalite: A reddish mineral composed of iron, zinc manganese, glucinum and sulphur occurring in massive octahedral crystals. Danalite is named after James Dwight Dana.

Depose: The rights or patent granted for an exclusive jewellery design in France.

Depth: The measure of a cut gemstone from the tip of the pavilion to the table.

Diadem: A semi circular jewelled ornamental headband or fillet worn by Eastern monarchs as a badge of royalty.

Diamante: A faceted, glittery glass bead-like a rhinestone or strass.

Diamond: A clear transparent precious gemstone composed of pure crystallized carbon which has been highly compressed over millions of years. Diamonds are the hardest substance known to mankind, rating a 10 on the Mohs scale. They are valued because it is difficult to produce a faceted diamond and when properly cut they have high refractivity and brilliance. The quality and value of a diamond is rated using the “4 C’s” of colour, cut, clarity and carat weight. (See individual listings). The diamond is the birthstone for April.

Diamond accent: Jewelry that has one or more diamonds with a combined carat weight of less than one-fourth of a carat.

Diamond Cut: In the context of gemstones, it means the same as “Brilliant cut”. In the context of diamond cut objects, (usually metal objects), it means that part of the object has been cut into a flat diamond shape.

Diamond-cut rope:  A chain in which a portion of the chain link is cut into a flat diamond-shaped face and polished to a high shine.

Diamonique: A registered trademark belonging to QVC Inc., and the brand name they choose to use for cubic zirconia.

Dichroism: The property possessed by some crystals of exhibiting two different colours when viewed from different angles. See Alexandrite, Ammolite, Iolite, Opal.

Dichroite: See Iolite.

Dinner ring: Another name for a Cocktail ring.

Diopside: A crystallized silicate of lime and magnesia found in igneous rocks which ranges in colour from clear, greyish green to almost black.

Dioxide: A compound containing two oxygen atoms per molecule.

Disc Earring: A round flat stud attached to the earlobe with a post and clutch.

Dispersion: (or “fire”). The prism of light refracted from within a finished Diamond or stone. The better a Diamond or stone is cut or faceted, the more colours are emitted from the stone as it is turned.

Distributor: Somebody, such as a drop-ship wholesaler, who markets or sells merchandise to a retailer rather than directly to the consumer. See also jobber.

Diva Fashion: The term “diva” was originally applied only to prima donna opera singers, but it has come to be used for any female who takes great pride in being a woman. “Diva fashion” is designed to be worn exclusively by women and is usually quite flashy, extravagant, and effeminate, exemplified by necklaces with lots of beads, pearls, and/or faceted stones.

Dog Collar: A broad choker worn tightly around the neck above the collarbone, just like a dog’s collar, that often incorporated parallel strands of pearls, beads, stones, diamonds, and platinum to great effect. It was made popular in the late Victorian and Edwardian periods by Queen Alexandra, who had a long graceful neck.

Domed: A piece of jewellery with a convex shape, thicker in the centre and tapering at the edges.

Door Knocker Earring: An earring with a hinged bottom that hangs below the earlobe.

Doublet: A method of combining two inexpensive stones and/or glass to imitate more valuable gemstones. For example, a green glass bottom with a garnet top will give the appearance of a fine emerald because the top is a natural gemstone with a cut cut facets, and a few natural imperfections, and the bottom is bright green which reflects throughout the stone.

Dress Clip: A brooch that uses a hinged clip or two-pronged pin to fasten the article to clothing. They were popular during the 1930s and 1940s and often made in pairs.

Dress Set: A set of gentleman’s jewellery composed of, usually matching, cufflinks, shirt studs, and sometimes vest buttons.

Drop: A small, usually teardrop-shaped, ornament which dangles from a piece of jewellery.

Drop Earring: Any earring which hangs below the earlobe. Also called a “Chandelier Earring” or “Dangle Earring”. Photo of heart-shaped dangle earring.

Duette: A combination of two clips on a pin back. Duette was a registered design by Coro, but is now used generically for this design.

dwt: The symbol for “pennyweight”, or 1/20th of a troy ounce, approx 1.555 grams.