spherical aberration The failure of the lens in a loupe to bring light into a consistent focus due to its shape. Also see chromatic aberration; triplet.
Spherical: Having a round, globular shape.
Symmetry: The overall unity and proportion of a stone's cut. Symmetry ranges from poor to excellent.
Table: The largest facet on the top of the diamond.
A spherical shell of color, pleochroic halo is present around radioactive impurity in a stone. This ring or halo said to represent a site where crystal structure has got changed by the absorption of energy of radioactive alpha particles .
A spherical pressed glass bead made in Czechoslovakia. No seam line should be visible and it should be optically perfectly round.
Above is an example of a vintage peridot Druk Bead.
DUCTILITY ...
First spherical pearls grown in Japan by Mikimoto
Cullinan diamond discovered in South Africa, presented to Edward VII on 1907 ...
A small spherical bead of metal
Granulation
The process of decorating a metal surface with tiny grains of metal ...
BEAD - A spherical object, with or without facets, distinguished by a hole drilled through the stone, usually on center.
BIWA PEARL - A mantle-tissue, nucleated, freshwater cultured pearl from Lake Biwa, Japan. Properly called a freshwater pearl.
Rounds - Spherical in shape
Spacer Bar - Jewelry finding used to hold multiple strands of beads in alignment and prevent tangling, are inserted at intervals while stringing the beads.
Bubbles are spherical or tear-shaped bubbles of gas captured in glass stones. Bubbles can also be found in resins (like plastics and amber), and much less-frequently in minerals (like quartz, emerald, and topaz).
Deposit of roughly spherical form with irregular protuberances
Geodes
Octahedral ...
~Mabe - Large, hemispherical cultured pearls grown against the inside shells of oysters rather than in the oysters' bodies. Less expensive than round cultured pearls due to their half-round shape, they are most popular in earrings, rings and brooches.
pisolitic Aggregate composed of small, spherical particles, larger in size and commonly more distorted than oolitic minerals. pit Type of mine where a large hole is dug in the ground to extract the valuable material.
The positive ions surrounded by the negatively charged electron resevoir retain an almost perfectly spherical shape. In a pure metal, these atoms are all of one element and are therefore all of the same atomic radius.
Shape-There are three main categories to pearl shape: spherical, symmetrical, and baroque. An example of a symmetrical pearl is an oval, while baroque pearls are irregular in shape.
Cultured pearls are often more spherical in shape.
Small, conical pits and protuberances with a white base are more common in cultured pearls than naturals, which instead are marked by small spherical defects.
A cultivated pearl usually begins its life when a spherical bead or a piece of mantle tissue is placed inside the mollusk. After this seeding process, the pearl farmers place the mollusks in wire-mesh baskets and suspend them in water.
It was said, however, that spherical bubbles sometimes appear in scientific gems. Another characteristic structural defect of practically every scientific gem may be utilized to distinguish them.
The so-called "spherical aberration" causes deviation from the true image. in the case of. very curved lenses the focus of rays at the edges lies nearer to the lens than the focus of the rays nearer to its axis.
Mabe " Large, hemispherical cultured pearls grown against the inside shells of oysters rather than in the oysters' bodies. These are taken from Mabe oysters, and give off a unique rainbow-colored sheen.
The Chinese were the first to culture a product from freshwater mussels, beginning as far back at the 13th century; however, their creations were not traditional pearls, but rather shell mabes (blister-shaped or hemispherical pearls that form against ...
Mabe Pearl: Also referred to as blister pearls, mabe pearls are half spherical cultured pearls formed on the inner shell of a mollusk and instead of in its body.
In 1893, Mikimoto cultured five semi-spherical pearls - the first pearls to be created by man. In 1896 he received a patent for production of hemispherical pearls, and after years of research succeeded in culturing perfectly round pearls in 1905.
This distortion is of two types: chromatic and spherical, and both types are caused by the curved shape of the lens, particularly at the edges where the curvature is the greatest.
With its intense orange color, unique flame structure, spherical shape, chatoyancy, porcellaneous luster, and durability, all these features combine to make melo pearl amongst the rarest gems in the world.
Formerly small and irregular in shape, recent advances in cultivation have made it possible to attain freshwater cultured pearls which are up to 10 mm in diameter and nearly spherical in shape.
A ring sizing machine consists of a series of conical or hemispherical cavities and a flat anvil that is used to press the ring into them. Anneal the ring and select an opening that is just large enough to contain the ring, as seen in figure 13.12a.
The shifting colors of opal, known as "fire," are the result of microscopic spherical structures within the stone. The structures reflect different wavelengths of light depending on their spacing, creating the opal's shimmering effect.
Spheres are initially sawed into cubes or dodecahedrons and then ground to shape between two pipes or rotating concave cutters, allowing the stone to rotate freely in any direction to form a perfect spherical shape.
By the late 1890s Kokichi Mikimoto had been awarded a patent for the process of culturing hemispherical pearls or "Mabes.
Dapping Punch
A punch with a spherical work tip. It is used to form domed pieces from discs of flat sheet metal. The metal is tapped into a steel dapping block that has hemispherical recesses.
Jewelry Frequently Asked Questions ...
The play of colors seen in opal is caused by the diffraction of light from regularly arranged transparent spherical particles of cristobalite, an amorphous silica, and the voids between these particles.
Non-cultured pearls created without human aid are extremely rare, especially when found in a well-shaped spherical form. For this reason, most pearls on the market are cultured pearls.
Modern granulation may use other metals but it was originally a gold working technique in which minute spherical grains of gold are applied and invisibly soldered to a metal surface forming decorative patterns.
The shifting colors seen in opal, called "fire," are the result of microscopic spherical structures within the stone which reflect different wavelengths of light depending on their spacing, creating the colorful shimmering effect.
Mabe a cultured pearl that is hemispherical (1/2 of a sphere)
Marcasites Crystalline pyrites cut to look like diamonds. Made through the 1700s and 1800s. Later 1900s marasites are made from cut metal or cut glass.
A steel tool (typically a cube) with round, hemispherical depressions used to form domes. The steel rods with matching domes on the ends are called dapping punches
die
A form into which sheet metal is pushed for forming ...
Shapes that are not spherical or even symmetrical are considered lower quality. Akoya, Tahitian, and South Sea pearls found in jewellery have a tendency to be the roundest, while Freshwater pearls can be oval or slightly off-round.
Such pieces were in the form of a spherical case (sometimes made of boxwood) with a hinged opening and having on the interior of each hemisphere a number of minute carved figures of saints or Biblical figures or scenes.
Round beads are generally spherical in shape. Round beads may be faceted like the bead shown at right, or may be smooth like a pearl.
round nose pliers ...
Mabe Pearl
Mabe pearls are large, hemispherical cultured pearls that grow attached to the inside shells of oysters. Mabe pearls are used in earrings, pins, and rings.
bead nucleation The use of a shell bead, usually spherical, implanted in the oyster to stimulate the growth of a cultured pearl, and forming the center of the pearl.
Orthorhombic (usually in radiating spherical clusters)
Envronment:
usually formed in pockets in volcanic basalts ...
Opal is formed of minute spherical particles constituting a gel which has the formula SiOx,n H2O, a silica with chemically combined water which may vary from 1 to 21 percent. Precious gemstone opal is approximately six to ten percent water.
dapping die - a cube made of iron and steel with various hemispherical indentations on its faces that are used with corresponding punches to make cup shaped forms in metal sheet.
Centering Bead Holes
I have a difficult time getting my holes centered in spherical (ball) shaped beads resulting in "wompie-goggled" (lopsided) beads. Does anyone have any ...
Glass is often used in jewelry, as beads (faceted or spherical), rhinestones and as poured glass.
GLASS PASTE ...
Fancy balls and beads: Balls and beads in shapes other than spherical, e.g.. beel shapes, ovals, cups etc.
Fancy Gallery: See "Gallery." ...
Mabe pearl: Cultured pearls grown against an oyster's shell rather than in an oyster's tissue. The result is a semi-spherical pearl with a relatively flat back.
Mabe: Hemispherical cultured pearl grown on the inside shell rather than within the flesh of the oyster. This pearl is used in rings and earrings where its flat back is not visible because it is attached to the jewelry piece.
A blister pearl (also called a bouton pearl) is a pearl that developed attached to the inside of a mollusk's shell. This type of pearl must be cut off the shell, and is therefore hemispherical.
Bead Setting: A variety of gemstone setting in which the clamps over the edge of the stone are formed by pressing into the metal a punch which has a hemispherical hollow, which forms the bead.
It is found frequently in small amounts in crevices in aluminous, low-grade metamorphic rocks and in limonite and phosphorite deposits. It is a hydrous phosphate of alumina, occurring usually in hemispherical radiated forms varying in colour from ...
These pearls are cultivated in mussels, in freshwater lakes and rivers in China, Japan and the United States. Due to their easy cultivation, freshwaters are fairly inexpensive. Shapes can be freeform, rice shaped, off-round or spherical, ...
Some amber products, rich in amber shapes and varieties, like necklace beads, spherical or flat pendants, beads on leather strip or just hemp or cotton string, gain in additional value in this way.
With both the tris- and hexoctahedron, the faces are often curved, resulting in a near spherical shape. The combination of dominant dodecahedron and subordinant hexoctahedron is not uncommon for garnet (fig. 3.12) ...
Saltwater pearls like the Japanese Akoya and South Sea pearls come from oysters and have a spherical mother of pearl seed. Fresh water pearls come from mussels and are seeded with an organic implant.
Akoya pearls are most commonly available in sizes ranging from 4 to 9 millimeters in diameter, generally spherical or roundish in shape, and are well suited to all kinds of jewelry as well as strung necklaces and bracelets.
Besides the popular round shape, there are stylish mabe (large hemispherical cultured pearls), fresh water (elongated in interesting shapes and colors), and South Sea (large cultured pearls 10 mm and up from Australian and Indonesian waters), ...
Natural pearls have no nucleus, but in the cultured variety the pearl is formed round a spherical bead inserted into the oyster shell. The oyster tries to render this intrusive body innocuous by sealing it off in a cyst of nacre.
 See also: Color, Jewel, Shape, Stone, Natural
  
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