Radiant cut: A rectangular gemstone with a total of 70 facets combining the shape of an emerald cut and the sparkle of a Brilliant cut.

Ratchet bezel: A bezel that can turn clockwise or counter-clockwise and clicks with a ratchet action as it rotates.

Rattles:  Silver rattles were made for babies in the 18th and 19th centuries.  They had bells and corals (for teething) attached to them.

Red Gold: See Rose Gold.

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

Refraction: The action of changing the direction of a light wave, so the light enters the object in one direction, and leaves it in another.

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: A kind of Acrostic jewelry, meaning jewelry where the first letter of each type of stone spells out a word. In this case, a Ring or brooch set with a Ruby, Emerald, Garnet, Amethyst, Ruby, and a Diamond so that the first letter of each gemstone spelled out "Regard".

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

Renaissance: 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.

Repoussage : A technique of embossing a metal sheet.  Relief on the metal is made by hammering a design from the back, so that the decoration projects. Then it is finished by polishing from the front with a chasing hammer, producing a three-dimensional bas-relief surface. An example of Repousse is the Statue of  Liberty. A picture example of repousse  -

  - the technique of embossing metal.

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.

Rhinestone: A faceted stone made of glass.

Rhodium: A metal that is part of the platinum family but is liquid in its raw natural state not not solid like platinum. Rhodium can be applied to base metals, gold, sterling silver, or some other alloy, to give it a shiny white surface like platinum. This process was popular in the 30's and 40's, is very durable, and very expensive.

Rhodochrosite: A medium to light pink opaque stone with cream or creamy-pink banding resembling a pink version of malachite.

Rhodolite: A rose-red to pale violet variety of pyrope garnet.

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.

Ring: A piece of jewelry worn on a finger. See Band, Betrothal Ring, Bridal Set, Charm Ring, Cigar Band, Claddagh Ring, Class Ring, Cluster Ring, Cocktail Ring, Comfort Fit, Compass Ring, Dinner Ring, Engagement Ring, Eternity Ring, Faith Ring, Fede Ring, Poesy, Poison Ring, Prayer Ring, Ring Guard, Ring Size, Shank, Shoulder, Signet, Stack Rings, Three Stone Diamond Ring.

Ring brooch: A type of brooch similar to a penannular brooch, but with a complete ring to which is usually hinged a horizontal pin slightly longer than the diameter of the brooch. The point of the pin rests on the ring opposite the hinge, and the brooch is worn by pulling the fabric up inside the ring, passing the pin through it twice and then pulling the fabric tight so that it holds the pin in place.

Ring guard: A Ring worn above another Ring to keep it from slipping off the finger.

Ring Size: A measurement of how large the Ring needs to be to fit on a person's finger. The average Ring size for women is 6. The average Ring size for men is 10.

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.

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

Rock Crystal: see Quartz.

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.

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 Cut: A style of diamond cutting or other transparent gemstone that produces a gem with a flat base and triangular facets that rise to form a dome. This style of cut has been in use since the 16th century. This was the popular cut until the Italian Vincenzo Peruzzi invented the Brilliant Cut about 1700.

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

Rose gold:  An alloy of gold mixed with copper, which gives it a red tint.

Rose Quartz: A translucent milky pink variety of Quartz.

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

Rotational Axis: See Axis of Symmetry.

Round Brilliant Cut: See Brilliant cut.

Rubellite: Red Tourmaline.

Ruby: One of the four precious gemstones along with Diamonds, Emeralds and Sapphires. Ruby is a member of the corundum family whose color comes from chromium oxide in the stone. Although corundum can come in many colors, rubies are, by definition, red. Rubies have been synthesized since at least 1890 and can only be distinguished from natural rubies by trained gemologists. Rubies are extremely hard, a 9 on the Mohs scale, second only to diamonds. Fine rubies of good color can be more valuable than diamonds, For centuries, rubies have symbolized beauty, charity, love, passion, power, and royalty. In some countries, engagement rings are set with rubies instead of diamonds. The ruby is the birthstone for July.

Rutilated quartz: Quartz crystals with inclusions made up of rutile crystals, (which resemble fine reddish-brown, red, and sometimes yellowish hairs), imbedded in the quartz.