Rhodonite is an attractive mineral that is primarily known as an ornamental stone but is often seen in jewelry in the form of beads or cabochons. This mineral easily falls into the category of rare and exotic, making it highly prized by collectors of specimens and gemstones. Its name, derived from two Greek roots, means "rose-colored stone." Rhodonite, which is commonly found in massive or granular forms, is most often translucent to opaque in appearance. On rare occasion, transparent, gem-quality material may be found. Rhodonite's natural color ranges from pink to rose red to brownish red, often with blackish veins throughout.
Rhyolite is a volcanic rock similar in its chemistry to granite. Most rhyolites are porphyritic, with larger crystals in a fine-grained matrix of crystals too small to be seen with the naked eye. Rhyolite is silica-rich, giving it a light range of color, often found with banding throughout. This beautiful stone is often used in ornamentation.
Richterite is a member of the amphibole group of minerals, named after German chemist Hieronymus Richter. Typically, richterite is near colorless to brown. If richterite is dominantly composed of potassium, it can be blue. In South Africa, it is associated with another blue mineral of similar chemical composition, sugilite.
Rock describes an inorganic material that is an aggregate, or mixture, of minerals. Rocks are igneous, metamorphic, sedimentary or in rare cases extraterrestrial (meteorites and some tektites).
Roman Glass is actual glass that has been buried for 2,000-years in mineral-rich soil. Archeological sites located near Jerusalem serve as the main source of Roman glass, notably because Israel once served as a major glass-making center. A thin layer of patina naturally forms on the glass as minerals in the soil react with the glass. The natural process of oxidation creates the various shades of blues and greens on the surface. As the coloration depends on the mineral condition to which the glass is exposed, each piece is unique.
Rosalinda is found outside Tambo Colorado, Peru, and was introduced to the market in 2011. The white areas of the stone are made up of marialite which is a variety of scapolite. The pink inclusions are the mineral Piemontite which is a member of the epidote group.
Rose quartz is the pink variety of quartz. Rarely transparent, facet grade gems will usually display a beautiful misty appearance. This gem can be found in large sizes, and is often carved into ornaments and figurines.
One of the most desirable of all tourmaline varieties, rubellite is the pink to red variety of elbaite tourmaline, but crystals may also include brownish, orangey or purplish hues. Stones that exhibit pure red or slightly purplish red color are considered the most valuable. With the exception of ruby and red spinel, rubellite is the only other gem known to occur in such a rich, dark red color. Incredibly scarce, with 'eye clean' material even rarer, rubellite is one of those special gems that demands a place in your gemstone collection!
The sole birthstone for July, ruby is the brightest and boldest of all birthstones. Called ratnaraj, meaning the "King of Gems" by ancient Hindus, ruby's association with the blood of life has earned it powerful praise and high esteem since antiquity. Ruby is mentioned at least four times in the Bible, always in reference to beauty and wisdom. Its passionate red color makes ruby an ideal choice for a romantic gift that comes with a rich legacy.
Ruby in zoisite is a translucent to opaque rock composed of ruby crystals, green zoisite and black hornblende. The official name for this gem is "anyolite," from the Masai word anyoli, meaning "green." This gem is usually used as an ornamental stone due to its stunning color contrasts.
Rudraksha Seeds are used as a prayer beads in Hinduism. Rudraksha is loosely translated from Sanskrit as "Lord Rudra's teardrops".
Gemstones are usually treasured for their crystalline varieties that contain little or no inclusions. Some varieties, however, are favored because of their unique inclusions. One such variety is rutilated quartz. Striking in appearance, the thin, elongated red to golden rutile needles may form parallel to one another or have random distribution throughout the quartz. On rare occasions, needles may radiate in six different directions, creating a star-like pattern. Specimens exhibiting this pattern are the most highly prized of all.
The name rutile comes from the Latin rutilas, meaning "reddish," as this mineral is usually red to golden in color. Rutile forms in a wide array of habits. It is often seen as an inclusion within gems either as large needles that make bold patterns, or as fine, microscopic fibers that cause chatoyancy and asterism in gems. It is highly refractive and is occasionally found in facetable sizes.
The term saltwater pearl refers to the pearls that are harvested in marine environments such as bays, gulfs, and seas. South Sea, Tahitian, Akoya, and Sea of Cortez Pearls are the best known cultured saltwater varieties. Cultured saltwater pearls are more expensive than freshwater varieties.
Sandstone is a sedimentary rock composed of sand-sized grains. Often banded in appearance, sandstone is one of the most common types of sedimentary rock and is found throughout the world. It is often mined for use as a construction material or as a raw material used in manufacturing. This stone can be cut, polished and carved for a variety of both practical and ornamental purposes.
Sanidine is a potassium-rich feldspar which is related to amazonite (microcline) and orthoclase by its chemistry. Sanidine gems that display adularescence, a mystical internal glow, are called moonstone. Colorless to yellow and pale brown gems have been found in Germany, Mexico, and Madagascar.
September's birthstone has come a long way since the days when any and every blue stone was called a sapphire. Though its fame is shared with its "Big Three" counterparts ruby and emerald, sapphire has enjoyed a long run as one of the world's most beloved gemstones, earning itself a place of honor in crown jewels, royal accessories, museums, and even in modern royal engagement rings. Lest sapphire get too haughty, it has common uses as well. The rough polishing material on emery boards is made up of lower-quality corundum grains, strengthened with hematite, magnetite and quartz.
Sapphirine was so named because of its resemblance in color to blue sapphire, even though the two minerals have completely different chemical, optical and physical properties. Sapphirine is very rare, with small gems only faceted for collectors. This gem is know for blue color, but occasionally forms in a red-orange variety.
Sard is a translucent chalcedony that is light to dark reddish-brown. It is formed from the deposition of silica at low temperatures from silica-rich waters percolating through cracks and fissures in other rocks. Sard is darker and browner in tone than carnelian.
Scapolite's name is derived from Greek words meaning "rod" or "shaft" and "stone," which describes the shape of its crystals. Originally discovered in 1913 in the Mogok stone tract of upper Burma, scapolite has been found in many locations. However, it is typically found only in small pockets, leading to its status of rarity in the gemstone world. Scapolite is a mineral group of colorless, or translucent pink, orange, yellow, green, blue, violet or purple gemstones.
Scheelite, named for Swedish chemist C.W. Scheele is a calcium tungstate, a major source of tungsten. Most scheelite is fluorescent and ranges from blue to white in color. Spectacular, transparent crystals come from Austria, Italy, Brazil, Rwanda, and Colorado. Scheelite crystals often have high luster and fire that is almost adamantine.
Schorl is the most common species of tourmaline, however, it is not as commonly faceted as its brightly colored brothers and sisters because of its black color. Well-formed schorl crystals make striking mineral specimens and long, thin schorl crystals are frequently found in quartz, called "tourmalinated quartz."
Scolecite is a fascinating zeolite mineral. Its name is derived from the Greek word, skolex, meaning worm because under a flame, scolecite curls up like a worm. It shares the unusual properties of piezoelectricity and pyroelectricity with other gem minerals like tourmaline.
Selenite is the name for transparent, colorless to near colorless crystals of gypsum, a hydrous calcium sulfate that is found in a number of forms. The name "selenite" comes from the Greek word selene, meaning "moon", no doubt in reference to the gem's white glow. Gypsum, in all varieties, is very soft and has perfect cleavage so it should be handled with care.