Whether it's understanding gemological or jewelry terms in an article you're reading or simply gaining a greater understanding of the world of jewelry and gemstones, our Jewelry & Gem Dictionary is a handy reference guide. And, unlike most dictionaries, ours makes for interesting reading all on its own!

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

PADPARADSCHA SAPPHIRE
Padparadscha sapphires (also spelled padparadschah) are a rare pink-orange variety of corundum or the synthetic equivalent. These gems are mined in Sri Lanka and are usually heat treated to improve and intensify the color. The name padparadscha comes from the Sinhalese word for lotus flower. Hardness = 9, Specific Gravity = 4.

PALLADIUM
Palladium is a valuable, durable, and malleable light-gray metal used in some jewelry; it is related to platinum, but is less dense and has a lower melting point. Unlike platinum, palladium reacts when exposed to aqua regia, sulfuric, nitric, and hydrochloric acids. It also develops a tarnish when it is heated. Pallasium is not a shiny as platinum. Palladium was only isolated as an element in 1802 by William Hyde Wollaston and Smithson Tennant. It was first used in jewelry in 1939 (during World War 2, platinum was used for war purposes, and was not available for jewelry making - palladium was temporarily used as a substitute for platinum). White gold is sometimes alloyed with palladium (instead of nickel), resulting in a gray-white gold. After World War 2, palladium was rarely used in jewelry making because of some difficulties in working with it. Palladium was recently discovered to be useful in engine catalytic converters, and its price skyrocketed to over $700 per ounce (it had previously been much less expensive than platinum or gold) and is no longer practical to use as jewelry.

PARURE
A parure is a matching set of jewelry, usually containing a necklace, earrings, brooch and a bracelet (or two bracelets). See demi-parure.

PASTE
A term for imitation gemstones. Fine jewelry was often imitated in finely made copies to protect the wearer from theft, and these were referred to as "paste".

PATINA
Patina is the change of an object's surface layer that result from aging. Exposure to the air for an extended period of time oxidizes many metals, turning copper and bronze green, and gold reddish. Artificial patinas can be applied to newer objects by using acids or electrolytes.

PAVÉ (pah-VAY)
Pave settings are stones set very close together. The stones hide the underlying surface. In better pieces, claw settings are used; in less expensive pieces, the stones are simple glued in.

PAVILION
The pavilion is the lower part of a cut gemstone, below the girdle.

PEAR CUT
A pear cut gemstone (also called a drop cut) is teardrop shaped This type of cut is used for pendants, drop earrings, rings, and other pieces of jewelry.

PEARL
Pearls are organic gems grown within oysters and a few other mollusks. Pearls are formed when a foreign object (like a tiny stone) has made its way into the mollusk's shell. The mollusk secretes nacre, a lustrous substance that coats the intruding object. As thousands of layers of nacre coat the intruder, a pearl is formed; this process takes up to seven or eight years (an oyster's useful life span). The most valuable pearls are perfectly symmetrical, large, naturally produced, and have a shimmering iridescence (called orient luster). There are many types of pearls, including natural pearls (made with no human interference), cultured pearls (pearls made by inserting a bit of a mother-of-pearl) into [nucleating] a living oyster or by inserting a bit of foreign tissue), baroque pearls (irregularly-shaped pearls), freshwater pearls, seed pearls (tiny pearls), Biwa pearls (a type of freshwater pearl from Lake Biwa, Japan from the freshwater mussel, Hyriopsis schlegeli), blister pearls (grown attached to the shell), black pearls (gray to black pearls), Mabe pearls (cultivated blister pearls), etc. Pearls can be gently cleaned with mild soap and water. The biggest natural pearl, known as the "Pearl of Allah" or "Pearl of Lao-tse," weighs 14 pounds (6.4 kg).

PEARL SHAPE
An important characteristic in determining the value of a pearl. Shape is classified by various degrees of roundness, symmetry, or irregularity.

PEAR-SHAPED
Description of a shape of gems and pearl which is rounded on one end and tapered on the other.

PEG SETTING
A tiny hole is drilled halfway into the pearl and a metal bar is inserted and secured with adhesive.

PENDANT
A pendant is a hanging ornament. Necklaces, pins, and earrings often have a pendant.

PENDELIQUE
A pendelique cut in one that is lozenge shaped. This cut is frequently used for flawed stones. Pendelique cut stones are often used as pendants.

PERIDOT
Peridot (also known as the "evening emerald" and chrysolite) is a yellow-green semi-precious stone with an oily luster; peridot is a transparent, green form of olivine. Peridot exhibits double refraction; when you look through the stone, things appear double. For example, when looking into a faceted peridot gemstone, the number of bottom facets appears to be double the actual number of facets. Most peridots are from a volcanic island in the Red Sea, Zebergit/St. John, the "Serpent Isle." Peridots have been found in meteorites. Peridot has a hardness of 6.5. Peridot cat's eye also exists.

PIERCED WORK
Pierced work is jewelry (or other metal work) that has patterns cut out of the metal. Pierced work is done with a piercing saw, a tiny chisel, or a stamping machine (with a die as the pattern). When a saw is used, the pattern is drawn on the metal, then a small hole is drilled in each of the future holes. The saw is then used to cut out the desired areas.

PIN
A pin (also brooch) is an ornament that can be pinned to a garment.

PINCHBECK
Pinchbeck (also known as "false gold") is a alloy of copper that looks like gold. Pinchbeck was invented by the British watchmaker Christopher Pinchbeck (1672-1732) in the early 18th century. Pinchbeck consists of 83% copper and 17% zinc. Ironically, there have been many imitations of Pinchbeck (which itself is an imitation).

PINK TOPAZ
Pink Topaz (Aluminum silicate fluoride hydroxide) is a very hard pink gemstone. Pink topaz is usually created by irradiating common yellow topaz. Topaz has a hardness of 8 and a specific gravity of 3.5-3.6.

PLANE OF SYMMETRY
A plane of symmetry is a plane that divides a solid into two mirror-image pieces of the solid.

PLATING
Plating or electroplating (also called Galvanotechnics after its inventor, Luigi Galvani) is a process in which one metal is coated with another metal using electricity. In jewelry, inexpensive metals are frequently electroplated with more expensive metals, like gold (gold plating), copper (electrocoppering), rhodium (rhodanizing), chromium (chromium plating), or silver (silver plating). The thickness of the metal coat varies. Electrogilded coating is the thinnest (less than 0.000007 inches thick); gold-cased metals have a coating thicker that 0.000007 inches.

PLATINUM
Platinum is a very strong, dense precious metal with a white color. Platinum jewelry is usually 90%-95% pure, is very sturdy, and holds stones well. Platinum is related to iridium. Platinum is 60% heavier than gold. Iridium and platinum are frequently alloyed together, since the Irridium increases the workability of the platinum. Platinum was only discovered in the 1700's in Russia. Platinum is abbreviated Pt. and Plat.

PLEOCHROISM (From the Greek pleion, "more", and chros, "color")
Pleochroism is the property of having more than two colors, especially when viewed from different angles. In pleochroic minerals, a single stone will show many colors (in the case of Iolite, violet-blue, light blue, and yellow-gray will be visible). In optics, the selective absorption in crystals of light vibrating in different planes. Pleochroism is the general term for both dichroism, which is found in uniaxial crystals (crystals with a single optic axis), and trichroism, found in biaxial crystals (two optic axes). It can only be observed in doubly refracting crystals.

PLIQUE A JOUR
Plique a jour is a back-less enamel that is a bit like stained glass. In plique a jour, the enamel work is translucent (light shows through it) since the backing of the enamel is absent. Cells of enamel are surrounded by delicate wire. Plique a jour is made by shaping cloisonne wire on a thin sheet of metal (or mica). Enamel (powdered glass) is fired into the wire cells. After the enamel has melted and cooled, the backing (metal or mica) is peeled away and the translucent enamel is left suspended in a supporting framework of cloisonne wire.

POINT
A point is a hundredth of a carat (0.01) or 0.002 gram. A 0.50-carat diamond is said to weigh 50 points.

POLISH
Polish describes how smoothly the facets of a diamond have been polished, whether any marks are visible from the polishing wheel, and how defined the edges of each facet are. Since these characteristic are rarely visible to the unaided eye, for an excellent value, look for a polish grade of very good or good, though the higher grades of ideal and excellent are also recommended. Avoid diamonds with polish grades of fair or poor, as the quality of their polish may affect the brilliance of the diamond.

POROUS
Porous stones have tiny holes in them. These holes allow water, oils, and other substances to penetratethe stone, frequently changing their appearance over time. Many stones are porous, including turquoise.

POURED GLASS
Poured glass is a jewelry technique in which glass is suspended within a metal framework. The result is a stained-glass-like effect with translucent glass.

PRECIOUS STONE
A precious stone (also called a gemstone) is one that is valuable and rare.

PRINCESS CUT
A princess cut is a square-cut stone. This fancy cut is relatively new and is also known as a Quadrillion or Squarillion cut.

PRINCESS LENGTH
A princess length necklace (usually referring to a string of pearls) is 18" long.

PROMISE RING
A promise ring is a pre-engagement ring, usually with a relatively small stone.

SPJ's Favorite Sources
for Diamonds, Colored Gemstones, and Antique, Vintage & Estate Jewelry

Original Diamonds ¿ Artistic Colored Stones ¿ Multicolour ¿ FayCullen