Rainbow Calsilica
Rainbow calsilica is a newly-found, multi-colored, layered stone composed of calcium and silica. This stone has been recently used for Zuni fetish carvings and in some jewelry (beads and cabochon cut stones). Rainbow calsilica was only recently found in Mexico or Northern South America (it's origin remains mysterious). Some people theorize that this stone formed as a result of the runoff of mining or oil-drilling chemicals, and has only formed in the last 30 to 50 years (but this is uncertain).

Rainbow Obsidian
Rainbow obsidian is another name for obsidian that is iridescent.

Rainbow Opal
Rainbow opal is a type of precious opal that has curved bands of colors (that resemble rainbows).

Rainbow Topaz
Rainbow topaz (also called mystic topaz or mystic fire) is topaz that has been color enhanced by coating it with a fine layer of metal atoms (in a process called vacuum deposition). This stone has red, green, violet, and blue streaks. Mystic fire has a hardness of 8.

Rajaratna
The Rajaratna is the biggest-known "star ruby" (a ruby that exhibits an asterism, a six-pointed star of light, cut as a cabochon). It weighs 2,475 carats.

Ratchet Bezel
A bezel that can turn clockwise or counterclockwise and clicks with a ratchet action as it rotates.

Rati
The rati is an Indian unit of weight that is used for gemstones. A rati is equal to 0.91 carats. The rati has varied in the past (and in different regions).

Raviratna
The Raviratna is the biggest-known ruby. It weighs 3,600 carats.

Razza
Razza is a line of costume jewelry from the 1960s and early 1970s designed by Luke Razza. Razza's pieces are highly collectible; they are mostly figural (often depicting animals and signs of the zodiac) and are generally large in scale. Many Razza pieces incorporate plastic with the metal.

Reconstituted
This is a term applied to stones which are made by using small chips, powder and ground up low grade stones, binding or fusing them with a plastic resin (epoxy) and compressing them into blocks. The blocks are then cut into beads, cabochons, and slabs.
In some cases, the reconstituted stone is actually made from "real" turquoise, amber, lapis or similar stone, but often the reconstituted stones are nothing more than low grade rocks, like howlite, that have been dyed and compressed to look like the real gemstone.
Ambroid is a form of reconstituted amber made from real amber pieces, but is should be
classified as imitation because of the epoxy resin content. It is made from scraps and shavings of amber that are heated and pressed into large blocks. Insects found in ambroid are usually fully intact, without broken body parts, as they were dead when added to the block. Insects found in real amber usually have broken wings and legs caused when they tried to escape from the sticky tree resin.
Reconstituted turquoise is manmade from pulverized pieces of turquoise that are stabilized and compressed with plastic resins to which dye is added and should be sold as "simulated" or "imitation" turquoise. However, this form is often used in much of the mass produced inlay jewelry.

Reconstructed Stone
A reconstructed stone is one that is made from pieces of smaller stones or crystals). Reconstructed stones often have telltale air bubbles. For example, "Geneva rubies" (reconstructed rubies) are made from tiny ruby crystals that have been fused together. This type of stone is generally no longer manufactured (except reconstructed amber, which is stilll made) because synthetic stones are vastly superior to reconstructed stones.

Red Beryl
Red beryl is a is a rare, deep red variety of beryl. Gemstone-quality forms of this mineral are found in only one place in the world, in the Wah Wah Mountains, near Beaver, Utah, USA. Small crystals of this gem were first found in 1905 in the Thomas Range in Juab County, Utah. The mine bearing gemstone-quality red-beryl was found in the 1950's. The biggest red beryl crystal ever found was 14mm by 34mm, weighing about 54 carats. The average faceted red beryl gemstone weighs about 0.15 carats. Red beryl has a hardness of 7 - 8, a specific gravity of 2.66-2.70, and a refractive index of 1.564-1.574. The chemical formula Be3Al2SiO6, with other trace elements. Internal flaws in beryl gems can be hidden by treating the stone with oil (this is often not disclosed to the buyer).

Red Diamonds
Red diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; 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.

Red Gold
See Rose Gold.

Red Jasper
An opaque, rust-red color of jasper.

Refraction
When light enters a medium with a different optical density (like a gemstone), the light is bent at an angle (and also changes its speed).

Refractive Index
The refractive index is a measure of how light is refracted in a substance (like a gemstone). In doubly-refractive stones, the light is split into two light rays when it enters the stone, and the rays travel in different paths - so these stones have more than one refractive index.

Refractometer
A refractometer is a device that measures the refractive index of a gemstone.

Refractory
A material with a high melting point, which makes it useful as a barrier between the heat source and a material that you don't want to melt, like the sides of an oven, etc..

Regard
Regard jewelry uses the stones Ruby, Emerald, Garnet, Amethyst, Ruby, and Diamond to spell the word "REGARD." Regard jewelry was given as a token of affection. This sentimental style was popular during the Victorian era.

Relief
A kind of decoration that protrudes from the surface, like a cameo.

Rebaussabce
The period in western Europe from the mid fifteenth century to the industrial age. The word means "rebirth" and was characterized by a radical development in the arts, medicine, politics and sciences.

Renoir of California
"Renoir of California" is a US jewelry company that makes copper jewelry. Their line marked "Matisse" is enameled copper; their line marked "Renoir" does not have enamel. The enameled copper leaf pin above is marked Matisse adn was made by the "Renoir of California" company.

Repousse
Repousse is a method of decorating sheet metal in which designs are hammered into the back of the metal. Special punches are used to form the designs, which form in relief (raised designs) on the surface of the metal.

Resinous
A type of luster exhibited on gemstones like amber.

Reticulation
Used in the jewelry making process to create a textured surface with ridges, ripples and valleys. The process requires deft use of a torch to bring the metal to a high
temperature just below its actual melting point. The jeweler carefully moves the torch flame around the metal surface, "pulling" the almost flowing metal into various ridges.
This takes extreme concentration and patience, allowing the torch to remain directed in one area for a split second too long will cause the metal to melt and either form a hole or a "ball" of molten metal instead of realizing the desired effect. The pattern of valleys and ridges of a reticulated piece is unpredictable and trying to duplicate a pattern is impossible although a skillful craftsperson will be able to create something similar for perhaps an earring set.

Retro
Retro jewelry is chunky, geometric jewelry from the 1940's. Pink gold was often used in retro pieces.

Reverse Crystal Jewelry
(also called Essex crystal) A clear crystal is cut as a cabochon. A carving is made on the flat side, like an intaglio, and painted with a thin layer of mother of pearl to produce a three-dimensional effect.

Reverse-carved lucite
Reverse-carved lucite is lucite (a transparent plastic) that is carved on the back side. The incised areas are often painted, highlighting the carving. The pin pictured above is clear, reverse-carved lucite that is accentuated with yellow and green paint; the painted carving closely resembles tiny roses.

Rhinestones
Rhinestones are highly reflective glass made to imitate gemstones. The original rhinestones were quartz stones (rock crystal) obtained from the Rhine river. These stones were cut to resemble gemstones. The best rhinestones today are made of highly reflective leaded glass which is faceted and polished. The Trifari pin above has baguette cut and round cut rhinestones.

Rhodium
Rhodium is a white precious metal. Rhodium is extremely expensive and is often used to plate precious and base metals, giving jewelry a hard, platinum-like sheen.

Rhodochrosite
Rhodochrosite is a mineral whose color ranges from rose to pink to almost yellow or brown. Although it is very pretty, this stone is soft and brittle; it is used in jewelry and for carvings and figurines. Rhodochrosite is Manganese Carbonate; its chemical formula is MnCO3. Rhodochrosite has a hardness of 3.5 - 4.5 (glass has a hardness of 4) and a specific gravity of 3.5. Rhodochrosite is found in Argentina, Peru, Germany, Mexico, South Africa, Russia, Italy, USA (Colorado and Montana), and Romania. Rhodochrosite is not enhanced.

Rhodolite
Rhodolite (meaning "rose stone" in Greek) is a purple-red to pink-red variety of garnet. It is a combination of almandine and pyrope (it is sometimes called pyrope-almandine garnet). This silicate stone has a hardness of 7-7.5 and a specific gravity of 3.5 - 4.3. The formula for garnet is: A3B2(SiO4)3. Rhodolite is found in the US, Zimbabwe, Kenya, and Sri Lanka (Ceylon). Rhodolite is not enhanced.

Rhodonite
a glassy, opaque, pink to rose-red mineral, often with black inclusions, composed of crystalline manganese silicate. Named after the Greek word "rhodon" meaning "rose". It is found in the former Soviet Union, the U.S., India, and Australia and is usually used as an ornamental stone.

Rhombohedral
Resembling a prism with six four-sided facets.

Ribbed
An undulating ridged texture, like a person's rib cage showing through the skin.

Richelieu
Richelieu jewelry is made by Joseph H. Meyer Bros. company of Brooklyn, N.Y. THe Richelieu name was first used in April, 1911. Richelieu manufactures clips, rings, necklaces, bracelets, and other costume jewelry.

Ring
A ring is a piece of jewelry worn around the finger; rings have been worn on every finger, including the thumb. Rings have been worn through the ages, and often have significant meaning. Some rings include wedding and engagement rings (denoting commitment), signet rings (impressed with the owner's seal), bands (made from a ribbon of metal), rings denoting group membership (like Masonic rings or college rings), devotional rings (with religous meaning), and pugilist rings (pointed rings worn by boxers to harm their opponent).

Ring Guard
A ring worn above another ring to keep it from slipping off the finger.

Rings Sized
Rings are sized using a graduated cone (a mandrel) with markings denoting the ring sizes. The ring is put on the cone and its size is read where it fits snugly on the cone. To size a finger, a finger-ring gauge is used. The rings are marked with their size and the person determines which one fits well. Another, less accurate method, is a cardboard card with cut-out holes marked with the ring sizes. Sizes in the US and Europe are numerical; sizes in the UK are alphabetical. To determine the ring size of a finger using the circumference of the finger, or to determine the size of a ring given its diameter, the formulas are:
System Formula using Circumference Formula using Diameter
USA Circumference in mm = 36.107 + (2.5890*Ring Size) Diameter in mm = 11.4931 + (0.8241*Ring Size)
Europe Ring Size =Circumference in mm Ring Size = 3.1416 * Diameter in mm
UK Circumference in mm = 36.667 + 1.2368*Ring Size(where 1=A, 2=B, etc.) Diameter in mm = 11.6713 + [0.3937 * Ring Size(where 1=A, 2=B, etc.)]

Riveting
A method of joining two flat objects together by making a hole in each piece, then passing a pin with a large flat head, (composed of the same metal as the piece), through the holes. The pin is then pounded flat to secure it in place. This process was used in jewelry instead of soldering when it was not advisable to use heat or when one part was intended to swivel.

Riverstones
Riverstones are smooth, rounded pebbles found in rivers and on beaches. The action of the water and other rocks on riverstones polishes them naturally. Riverstones can be used as beads/stones in jewelry.

Riviere
A necklace composed of a single strand of gemstones of the same size and cut, usually Diamonds.

Robert
"Robert" and "Original by Robert" were costume jewelry marks used by the Fashioncraft Jewelry Company (founded by Robert Levey, David Jaffe, and Irving Landsman in the 1942. These high-priced, hand-made pieces are often complex, having beads and pearls, rhinestones, enamel, and/or floral designs; they are often similar to some Miriam Haskell pieces. Robert jewelry was used in some Hollywood films, including the 1952 movie "Viva Zapata." Robert pieces were produced until around 1975.

Rocaille
Rocaille is jewelry whose design is based on sea life, sea shells, or rocks.

Rock Crystal
Rock crystal is a transparent, crystalline mineral. Rock crystal is the purest form of quartz and a semi-precious stone.

Rocky Mountain Ruby
A Rocky Mountain ruby is actually a pyrope garnet (and not a ruby at all).

Rolled Gold
Rolled gold is a very thin sheet of gold that is laminated to a lesser metal (usually brass). The two layers of metal are heated under pressure to fuse them together. The sheet is them rolled into a very thin sheet and then used to make jewelry or other objects. Jewelry made from rolled gold wear well over time. Rolled gold pieces are marked rolled gold plate, R.G.P., or plaqué d'or laminé.

Rolo Link Chain
A chain composed of individually linked round or oval rings resembling a standard cable chain, but with thicker rings.

Rondella
A round metal disk, sometimes studded with stones, that is strung on a necklace as a spacer between beads.

Rondelle
A rondelle is a small disc used as a spacer in beadwork. Some rondelles are clear crystal discs, often used between colored crystal beads. Other rondelles are encircled with chanel-set diamonds or rhinestones.

Rope
A rope is a string of pearlsthat is over 40 inches long.

Rope Chain
A series of small oval-shaped links that are arranged in such a way that they make a spiral design resembling woven rope.

Rose de France
Rose de France is a recent name for a very pale variety of amethyst. It is also known as lavender amethyst. Rose de France has a hardness of 7.0. This pale lilac transparent gem is found worldwide and is a type of quartz. Rose de France is sometimes heat-treated in order to lighten its color and/or to remove smokiness.

Rose Cut
The rose cut (also called the rosette cut) for diamonds was invented in the 17th century and its used continued until the 18th century. The rose cut has a flat base and triangular facets (usually 24). This cut has little wastage of stone, but is not nearly as reflective as the brilliant cut, which was invented later.

Rose Finish
Jewelry finished so that it has the look of Rose Gold, but no actual gold content.

Rose Gold
Rose gold (also known as pink gold) is gold with a pink tinge. It has been alloyed with a mix of 90% copper and 10% silver.

Rose Quartz
Rose quartz is a form of quartz that ranges in color from pink to deep red.

Rotating Bezel
A bezel that can be turned to perform different timekeeping and mathematical functions.

Rotational Axis
See Axis of Symmetry.

Rough
Rough stones or crystals are in their natural state, they are neither cut nor polished.

Roulz
Roulz is a metal alloy that consists of about copper, nickel, and silver. Ruolz is named for the French chemist and musician Vicomte Henri de Roulz, who invented the alloy in the 1800s.

Round Brilliant Cut
See Brilliant cut.

Rubellite
Rubellite (sometimes spelled rubelite) is a red variety of tourmaline. Rubellite is red in both incandescent light and daylight, and is more valuable than other varieties of red tourmaline. Rubellite has a hardness of 7-7.5 and a specific gravity of 3.02-3.25. Rubellite is sometimes treated with fillers to increase the clarity of the stone.

Ruby
Rubies are precious stones and a member of the corundum family (Al2O3). Rubies range in color from the classic deep red to pink to purple to brown. Rubies are extremely hard; only diamonds are harder. During the renaissance, people thought that rubies could counteract poison. Laboratory-produced rubies were created in the 1890's; they are difficult to distinguish from natural rubies. The biggest ruby in the word is the Raviratna, which weighs 3,600 carats. Rubies have a hardness of 9 and a specific gravity of 3.9 - 4.1. Rubies are found in Afghanistan, Australia, Brazil, Cambodia, India, Myanmar (Burma), Malagasy Republic, Malawi, Pakistan, Sri Lanka (Ceylon), Tanzania, Thailand, United States, and Zimbabwe (Rhodesia).

Ruby Spinel
A ruby spinel (or spinel ruby) is deep red, transparent spinel (not a ruby).

Rumanite
Rumanite is a type of opal that is from Romania.

Russian Gold Finish
A Russian gold finish is a matte, antique-look finish. Miriam Haskell jewelry often has a Russian gold (plated) finish.

Ruthenium
Ruthenium (abbreviated Ruth or Ru) is a precious metal that belongs to the platinum group of metals. In jewelry, ruthenium is added to platinum alloys; about 5 to 10 perent ruthenium can be added to platinum to harden and strengthen the alloy. Ruthenium's atomic number is 44.

Rutilated Quartz
Rutilated quartz is a type of rock crystal which contains long, fine needles of rutile crystals (titanium dioxide). This beautiful stone is usually cut as a cabochon. It is also known as Venus' Hair Stone, Cupid's darts, and Fleches d'amour (arrows of love).