History of the Star of David

Star of David

The Star of David is a poplar theme for Jewish Jewelry.

The six points of the Star of David symbolize God's rule over the universe in all six directions: north, south, east, west, up and down.

Originally, the Hebrew name Magen David -- literally "Shield of David" -- poetically referred to God. It acknowledges that our military hero, King David, did not win by his own might, but by the support of the Almighty. This is also alluded to in the third blessing after the Haftorah reading on Shabbat: "Blessed are you God, Shield of David."

The Star of David (Magen David in Hebrew or Mogen Dovid in Ashkenazi Hebrew, Shield of David, Solomon's Seal, or Seal of Solomon) is a generally recognized symbol of Judaism and Jewish identity. Geometrically it is a hexagram. It is also known colloquially as the Jewish Star. With the establishment of the State of Israel the Jewish Star on the flag of Israel has also become a symbol of Israel.

Origin

The shield of David is not mentioned in rabbinic literature. Notably, not a single archeological proof exists as yet concerning the use of this symbol in the Holy Land in ancient times, even after King David. A David's shield has recently been noted on a Jewish tombstone at Taranto, in Southern Italy, which may date as early as the third century of the common era. The earliest Jewish literary source which mentions it, the Eshkol ha-Kofer of the Karaite Judah Hadassi (middle of the 12th century), says, in ch. 242: "Seven names of angels precede the mezuzah: Michael, Gabriel, etc.... Tetragrammaton protect thee! And likewise the sign called 'David's shield' is placed beside the name of each angel." It was, therefore, at this time a sign on amulets.

In magic papyri of antiquity, pentagrams, together with stars and other signs, are frequently found on amulets bearing the Jewish names of God, and used to guard against fever and other diseases. Curiously enough, only the pentacle appears, not the hexagram. In the great magic papyrus at Paris and London there are twenty-two signs side by side, and a circle with twelve signs, but neither a pentacle nor a hexagram. The syncretism of Hellenistic, Jewish, and Coptic influences probably did not, therefore, originate the symbol. It is possible that it was the Kabbalah that derived the symbol from the Templars. Kabbalah makes use of this sign, arranging the Ten Sephiroth, or spheres, in it, and placing it on amulets.

A manuscript Tanakh dated 1307 and belonging to Rabbi Yosef bar Yehuda ben Marvas from Toledo, Spain, was decorated with a Shield of David.

In the synagogues, perhaps, it took the place of the mezuzah, and the name "shield of David" may have been given it in virtue of its presumed protective powers. The hexagram may have been employed originally also as an architectural ornament on synagogues, as it is, for example, on the cathedrals of Brandenburg and Stendal, and on the Marktkirche at Hanover. A pentacle in this form is found on the ancient synagogue at Tell Hum.

In 1354, King of Bohemia Charles IV prescribed for the Jews of Prague a red flag with both David's shield and Solomon's seal, while the red flag with which the Jews met King Matthias of Hungary in the 15th century showed two pentacles with two golden stars (Schwandtner, Scriptores Rerum Hungaricarum, ii. 148). The pentacle, therefore, may also have been used among the Jews. It occurs in a manuscript as early as the year 1073 (facsimile in M. Friedmann, Seder Eliyahu Rabbah ve-Seder Eliyahu Ztṭa, Vienna, 1901).

In 1460, the Jews of Ofen (Budapest, Hungary) received King Mathios Kuruvenus with a red flag on which were two Shields of David and two stars. In the first Hebrew prayer book, printed in Prague in 1512, a large Shield of David appears on the cover. In the colophon is written: "Each man beneath his flag according to the house of their fathers... and he will merit to bestow a bountiful gift on anyone who grasps the Shield of David." In 1592, Mordechai Maizel was allowed to affix "a flag of King David, similar to that located on the Main Synagogue" to his synagogue in Prague. In 1648, the Jews of Prague were again allowed a flag, in acknowledgment of their part in defending the city against the Swedes. On a red background was a yellow Shield of David, in the centre of which was a Swedish star.

Jewish lore links the symbol to the "Seal of Solomon", the magical signet ring used by King Solomon to control demons and spirits. Jewish lore also links the symbol to a magic shield owned by King David that protected him from enemies. Following Jewish emancipation after the French revolution, Jewish communities chose the Star of David to represent themselves, comparable to the cross used by most Christians. The star is found on the flag of Israel.

The shape of the star is an example of the hexagram, a symbol which has significance for other belief systems. The hexagram pre-dates its use by Jews. Its most prevalent usage outside of Judaism was and is the occult.

Another theory about the origin of the shape is that it is simply 2 of the 3 letters in the name David. In its Hebrew spelling, David contains only 3 characters, 2 of which are "D" (or "Dalet", in Hebrew). In ancient times, this letter was written in a form much like a triangle, similar to the greek letter "Delta", with which it shares a sound and the same (4th) position in their respective alphabets, as it does with English. The symbol may have been a simple family crest formed by flipping and juxtaposing the two most prominent letters in the name.

So whether it is a blue star waving proudly on a flag, or a gold star adorning a synagogue's entrance, the Star of David stands as a reminder that for the Jewish people... in God we trust.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Star of David.

Jewelry: Cubic Zirconia

Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. The synthesized material is hard, optically flawless and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO4).

Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained the most gemologically and economically important diamond simulant since 1976. Its main competition as a synthetic gemstone is the more recently cultivated material moissanite.

Technical aspects

Cubic zirconia is, as its name would imply, crystallographically isometric, and as diamond is also isometric, this is an important attribute of a would-be diamond simulant. Synthesized material contains a certain mole percentage (10-15%) of metal oxide stabilizer. During synthesis zirconium oxide would otherwise form monoclinic crystals, as that is its stable form under normal atmospheric conditions. The stabilizer is required for cubic crystal formation; it may be typically either yttrium or calcium oxide, the amount and stabilizer used depending on the many recipes of individual manufacturers. Therefore the physical and optical properties of synthesized CZ vary, all values being ranges.

It is a dense substance, with a specific gravity between 5.6 - 6.0. Cubic zirconia is relatively hard, at about 8.5 on the Mohs scale - nowhere near diamond, but much harder than most natural gems. Its refractive index is high at 2.15 - 2.18 (B-G interval) and its luster is subadamantine. Its dispersion is very high at 0.058 - 0.066, exceeding that of diamond (0.044). Cubic zirconia has no cleavage and exhibits a conchoidal fracture. It is considered brittle.

Under shortwave UV cubic zirconia typically luminesces a yellow, greenish yellow or "beige." Under longwave UV the effect is greatly diminished, with sometimes a whitish glow being seen. Colored stones may show a strong, complex rare earth absorption spectrum.

History

Since 1892 the yellowish, monoclinic mineral baddeleyite had been the only natural form of zirconium oxide known. Being of rare occurrence it had little economic importance.

The extremely high melting point of zirconia (2750°C) posed a hurdle to controlled single-crystal growth, as no existing crucible could hold it in its molten state. However, stabilization of zirconium oxide had been realized early on, with the synthetic product stabilized zirconia introduced in 1930. Although cubic, it was in the form of a polycrystalline ceramic: it was made use of as a refractory material, highly resistant to chemical and thermal (up to 2540°C) attack.

Seven years later, German mineralogists M. V. Stackelberg and K. Chudoba discovered naturally occurring cubic zirconia in the form of microscopic grains included in metamict zircon. Thought to be a byproduct of the metamictization process, the two scientists did not think the mineral important enough to formally name. The discovery was confirmed through x-ray diffraction, proving a natural counterpart to the synthetic product exists.

As with the majority of diamond imitations, the conceptual birth of single-crystal cubic zirconia began in the minds of scientists seeking a new and versatile material for use in lasers and other optical applications. Its evolution would eclipse earlier synthetics, such as synthetic strontium titanate, synthetic rutile, YAG (Yttrium Aluminium Garnet) and GGG (Gadolinium Gallium Garnet).

Some of the earliest research into controlled single-crystal growth of cubic zirconia occurred in 1960s France, much work being done by Y. Roulin and R. Collongues. The technique developed saw molten zirconia contained within itself with crystal growth from the melt: The process was named cold crucible, an allusion to the system of water cooling used. Though promising, these pursuits yielded only small crystals.

Later, Soviet scientists under V. V. Osiko at the Lebedev Physical Institute in Moscow perfected the technique, which was then named skull crucible (an allusion either to the shape of the water-cooled container or to the occasional form of crystals grown). They named the jewel Fianit, but the name was not used outside of the USSR. Their breakthrough was published in 1973, and commercial production began in 1976. By 1980 annual global production had reached 50 million carats (10,000 kg).

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia Cubic Zirconia.

History of Jewelry: Cubic Zirconia

Tourmaline

Tourmaline

The mineral tourmaline is chemically one of the most complicated silicate minerals. It is a complex silicate of aluminum and boron but because of isomorphism replacement (solid solution) its composition varies widely with iron, magnesium and lithium and other elements entering into the combination to a greater or lesser extent.

Tourmaline belongs to the trigonal crystal system and occurs as long, slender to thick prismatic and columnar crystals that are usually triangular in cross-section. Interestingly the style of termination at the ends of crystals is asymmetrical, called hemimorphism. Small slender prismatic crystals are common in a fine grained granite called aplite often forming radial daisy like patterns. Tourmaline is distinguished by its three sided prisms, no other common mineral has three sides. Prisms faces often have heavy vertical striations that produce a rounded triangular effect. Tourmaline is rarely perfectly ethereal. An exception were the fine dravite tourmalines of Yinnietharra western Australia. The deposit was discovered in the 1970s but it is now exhausted.

All hemimorphy crystals are piezoelectric and often also pyroelectric. Tourmaline crystals when warmed become positively charged at one end and negatively charged at the other. Due to this effect tourmaline crystals in collections may attract unsightly coatings of dust when displayed under hot spotlights. Tourmalines unusual electrical properties made it famous in the early 18th century. Brightly colored Sri Lankan gem tourmalines were brought to Europe in great quantities by the Dutch East India Company to satisfy demand as curios and gems. At the time it was not realized that schorl and tourmaline were the same mineral.

Tourmaline has a wide variety of colors. Usually it is iron rich black to bluish-black to deep brown, magnesium rich varieties are brown to yellow, and lithium rich tourmalines are practically any color of the rainbow, blue, green, red, yellow or pink etc. but most rarely of all it is colorless. Bi-colored and multicolored crystals are relatively common, reflecting variations of fluid chemistry during crystallization. Crystals maybe green at one end and pink at the other or green on the outside and pink inside, this type is called watermelon tourmaline. Some forms of tourmaline are diachronic, in that they appear to change color as when viewed from different directions.

The most common variety of tourmaline is schorl, it was first described by Mathesius in 1524. It may account for 95% or more of all tourmaline in nature. The word tourmaline is corruption of the Ceylonese word turamali meaning stone attracting ash. The meaning of the word schorl is a mystery but it maybe a Scandinavian word.

Tourmaline is found in two main geological occurrences. Igneous rocks, in particular granite and granite pegmatite and in metamorphic rocks such as schist and marble. Schorl and lithium rich tourmalines are usually found in granite and granite pegmatite. Mg rich tourmalines, dravites, are generally restricted to schists and marble. Also, tourmaline is a durable mineral and can be found in minor amounts as grains in sandstone and conglomerate.

Tourmaline is used in jewelry, pressure gauges and specialist microphones. In jewelry, blue indicolite is the most expensive followed by green verdelite and pink rubellite. Ironically the rarest variety, colorless achroite is not appreciated and is the least expensive of the transparent tourmalines.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Tourmaline.

History of Jewelry: Tourmaline

Jewelry: Topaz

Topaz

This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation).

The mineral topaz is a silicate of aluminium and fluorine with the chemical formula (AlF)2SiO4. It is orthorhombic and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. It has an easy and perfect basal cleavage and so gemstones or other fine specimens should be handled with care to avoid developing cleavage flaws. The fracture is conchoidal to uneven. Topaz has a hardness of 8, a specific gravity of 3.4-3.6, and a vitreous lustre. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. They may also be white, gray, green, blue, or reddish-yellow and transparent or translucent. When heated, yellow topaz often becomes reddish-pink. It can also be irradiated, turning the stone a light and distinctive shade of blue.

Topaz is found associated with the more acid rocks of the granite and rhyolite type and may be found with fluorite and cassiterite. It can be found in the Ural and Ilmen mountains, Czech Republic, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and the United States.

The name "topaz" is derived from the Greek topazos, "to seek," which was the name of an island in the Red Sea that was difficult to find and from which a yellow stone (now believed to be a yellowish olivine) was mined in ancient times. In the Middle Ages the name topaz was used to refer to any yellow gemstone, but now the name is only properly applied to the silicate described above.

Topaz is also the birthstone of November.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Topaz.

History of Jewelry: Topaz

Jewelry: Diamonds

As a gemstone, Diamond's single flaw (perfect cleavage) is far outdistanced by the sum of its positive qualities. It has a broad color range, high refraction, high dispersion or fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability. Diamond is the April Birthstone.

In terms of it's physical properties, diamond is the ultimate mineral in several ways:

• Hardness: Diamond is a perfect "10", defining the top of the hardness scale.
• Clarity: Diamond is transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) than is any other solid or liquid substance - nothing else even comes close.
• Thermal Conductivity: Diamond conducts heat better than anything - five times better than the second best element, Silver!
• Melting Point: Diamond has the highest melting point (3820 degrees Kelvin)!
• Lattice Density: The atoms of Diamond are packed closer together than are the atoms of any other substance!

Opal

Opal

opal, a mineral consisting of poorly crystalline to amorphous silica, SiO2·nH2O; the water content is quite variable but usually ranges from 3% to 10%. Common opal is usually colorless or white, but it may be gray, brown, yellow, or red; the color is due to fine-grained impurities. Opal is formed at low temperatures from silica-bearing waters and can occur in fissures and cavities of any rock type. Precious, or gem, opal has a rich iridescence and remarkable play of changing colors, usually in red, green, and blue. This is the result of a specific internal structure consisting of regularly packed uniform spheres of amorphous silica a few tenths of a micron in diameter; sphere diameter and refractive index determine the range of colors displayed. The greater part of the world's supply of precious opal comes from the Coober Pedy and Andamooka fields in South Australia. The original source, known in Roman times, was in what is now E Slovakia. Precious opal has also been mined in Honduras, Mexico, and the Virgin Valley in Nevada. Fire opal is a bright red transparent or translucent opal that may or may not show a play of color.

Precious opal

Precious opal shows a variable interplay of internal colours and does have an internal structure. At the micro scale precious opal is composed of hexagonal or cubic closely packed silica spheres some 150 to 300 nm in diameter. These ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of opal (Klein and Hurlbut, 1985, p. 444). In addition, microfractures may be filled with secondary silica and form thin lamellae inside the opal during solidification. The term opalescence is commonly and erroneously used to describe this unique and beautiful phenomenon, which is correctly termed play of color. Contrarily, opalescence is correctly applied to the milky, turbid appearance of common or potch opal. Potch does not show a play of color.

The veins of opal displaying the play of color are often quite thin, and this has given rise to unusual methods of preparing the stone as a gem. An opal doublet is a thin layer of colorful material, backed by a black mineral, such as ironstone, basalt or obsidian. The darker backing emphasizes the play of color, and results in a more attractive display than a lighter potch. Given the texture of opals, they can be quite difficult to polish to a reasonable lustre. The triplet cut backs the colored material with a dark backing, and then has a cap of clear quartz (rock crystal) on top, which takes a high polish, and acts as a protective layer for the comparatively delicate opal.

Opal is symbolic of love, death, and breaking up. In the Medieval Times, the opal stone was given by a male to an unwanted female mate.

Common opal

Besides the gemstone varieties that show a play of color, there are other kinds of common opal such as the milk opal, milky bluish to greenish (which can sometimes be of gemstone quality); resin opal, honey-yellow with a resinous lustre; wood opal, caused by the replacement of the organic material in wood with opal; menilite brown or grey; hyalite, a colorless glass-clear opal sometimes called Muller's Glass; geyserite, (siliceous sinter) deposited around hot springs or geysers; and diatomite or diatomaceous earth, the accumulations of diatom shells or tests.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Opal.