Material Digest

Agate is a banded form of finely-grained, microcrystalline Quartz. The lovely color patterns and banding make this translucent gemstone very unique. Agates can have many distinctive styles and patterns, but each Agate is unique in its own habit, with no two Agates being the same.

Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a reddish-orange color.

Copper is used as a conductor of heat and electricity, as a building material, and as an ingredient of various metal alloys, such as sterling silver used in to make jewelry.

Hawk’s eye is a blue-gray to blue-green opaque gemstone variety of fibrous quartz. Hawk’s eye is actually a pseudomorph of quartz. A pseudomorph is one mineral that changes into another mineral over time. In the case of hawk’s eye, it began its life as crocidolite and was later transformed into quartz.

Crocidolite is a fibrous blue mineral belonging to the riebeckite family of amphibole silicates. It is considered to be one of the several forms of asbestos.

The transformation of hawk’s eye begins as quartz slowly becomes embedded between the fibers of crocidolite, eventually completely replacing it while retaining the fibrous shape of the original mineral.

Howlite is a borate mineral which forms as irregular nodules which can appear in the shape of a cauliflower head. Transparent howlite crystals are extremely rare and are small but the nodules can occur in masses of over 50 kilograms. Howlite has the appearance of white marble or porcelain with a sub-vitreous luster. It is opaque and white or grey with grey, black or dark brown veins running through it. Gemstone quality howlite can be interspersed by the darker matrix (which appears as the veins), or it can be matrix-free and pure white. Howlite is best known for imitating other gemstones. Due to its porous nature, howlite can absorb dye well, which means it can be sold as turquoise, red coral, or lapis lazuli.

Jade is best known as a green ornamental stone. Its colors vary from light to dark green, but it may also be other colors such as white, gray, and purple. Jade is actually the gemstone name for two different mineral forms, Jadeite and Nephrite. These two minerals can be identical in appearance and are similar in their physical properties, and until modern times no distinction was made between the two different types of Jade. While Nephrite is generally only green, cream, or white, Jadeite colors can range through the color spectrum with more exotic colors.

Jasper is an opaque variety of Chalcedony, and is usually associated with brown, yellow, or reddish colors, but may be used to describe other opaque colors of Chalcedony such as dark or mottled green, orange, and black. Jasper is almost always multicolored, with unique color patterns and habits.

Labradorite is an important feldspar gemstone. It often displays a beautiful iridescent play of colors, which can move as the stone is rotated. Labradorite gemstones usually have a dark base color with metallic-looking color plays of blue, green, yellow, and red. This iridescent effect is commonly known as labradorescence, and is named after this stone. It is caused by internal fractures that reflect light back and forth, dispersing it into different colors.

Lapis Lazuli is a deep blue opaque gemstone, used in antiquity and continuously used throughout the generations. It still continues to be popular today and remains one of the most important opaque gemstones. Lapis Lazuli is chiefly composed of the mineral Lazurite, with additional other minerals including white Calcite and sparkling specks of Pyrite.

Onyx is a gemstone whose description can have several connotations. Its most accepted gemstone definition describes a solid black Chalcedony or a banded or layered black and white Chalcedony. The term Onyx is occasionally used to describe any engraved stone with a solid color base, or it may describe any banded gemstone with parallel banding. In its solid black form, Onyx is the most traditional black gemstone.

Pietersite is a rare dark-gray or reddish breccia aggregate (rock made up of fragments embedded in a matrix), comprised mostly of hawk’s eye and tiger’s eye. Pietersite from Namibia was first described in 1962. Pietersite is now used as a general term to describe brecciated tiger’s eye.

Pietersite is characterized by its distinctive swirls or streaks of gold or orange, due to the crocidolite inclusions within a microcrystalline silica host. Crocidolite is the same material responsible for tiger’s eye chatoyancy. When polished, the inclusions in pietersite exhibit chaotic chatoyancy whereas in tiger’s eye, the inclusions are arranged in parallel lines and give the appearance of a continuous line.

Prehnite gemstones are usually light green in color, with a whitish hue or yellowish tinge. Deep green gemstones are not common. Prehnite gemstones often appear cloudy or velvety, and rarely fully transparent. They may also contain colors in zones of lighter and darker green.

Prehnite gemstones are usually light green in color, with a whitish hue or yellowish tinge. Deep green gemstones are not common. Prehnite gemstones often appear cloudy or velvety, and rarely fully transparent. They may also contain colors zones of lighter and darker green.

Smoky Quartz is the brown “smoky” variety of Quartz. It ranges in color from light grayish-brown to deep black. Smoky Quartz can be opaque, but is almost always transparent to translucent, even when in its darkest color shade. Smoky Quartz is very common and was never a historically important gemstone. Only in very recent times has it become a popular gemstone.

Rutilated Quartz is a transparent Quartz with golden yellow Rutile inclusions that are in hairlike growths. The Rutile inclusions range from thin, sparse, and parallel, to thick, dense, and crisscrossed, and everything in-between. Each Rutilated Quartz gemstone is unique in its pattern of Rutile inclusions.

Smoky Quartz is the brown “smoky” variety of Quartz. It ranges in color from light grayish-brown to deep black. Smoky Quartz can be opaque, but is almost always transparent to translucent, even when in its darkest color shade. Smoky Quartz is very common and was never a historically important gemstone. Only in very recent times has it become a popular gemstone.

Fine silver has a millesimal fineness of 999. Also called pure silver, or three nines fine, fine silver contains 99.9% silver, with the balance being trace amounts of impurities. This grade of silver is used to make bullion bars for international commodities trading and investment in silver. In the modern world, fine silver is understood to be too soft for general use.

Argentium Silver 935 is a modern sterling silver alloy, containing 93.5% silver. The traditional sterling alloy (92.5% silver + 7.5% copper) is modified by removing some of the copper and adding the metalloid germanium. Argentium Silver 960 is a higher-purity jewelry alloy also containing germanium. It meets the standard for Britannia silver hallmarking which is 95.84% silver.

Sterling silver has a millesimal fineness of 925. The sterling silver alloy is 92.5% pure silver and 7.5% copper or other metals.

Tiger’s eye, also called tiger eye, is a chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown color and a silky luster. As members of the quartz group, tiger’s eye and the related blue-colored mineral hawk’s eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered amphibole fibers that have mostly turned into limonite

Tiger iron is an altered rock composed chiefly of tiger’s eye, red jasper, and black hematite. The undulating, contrasting bands of color and luster make for an attractive motif and it is mainly used for jewelry-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to knife hilts.

Tiger iron is mined primarily in South Africa and Western Australia. Tiger’s eye is silicon dioxide and is coloured mainly by iron oxide. The specific gravity ranges from 2.64 to 2.71. It is formed by the alteration of crocidolite.

Tourmaline is the most colorful of all gemstones. It occurs in all colors, but pink, red, green, blue and multicolored are its most well-known gem colors. Scientifically, tourmaline is not a single mineral, but a group of minerals related to their physical and chemical properties. The mineral Elbaite is the member of the Tourmaline group that is responsible for almost all the gem varieties. Three other members of the group – Schorl, Dravite, and Liddicoatite, are seldom used as gemstones.