Why Tungsten Carbide Jewelry?
What is Tungsten? Tungsten is a metal found in several ores and has robust physical properties. It has the highest melting point of all the non-alloyed metals and is second to carbon of the elements.

Tungsten carbide is one of the most durable and scratch resistant jewelry available.
What gives Tungsten Carbide it's hard, scratch resistant property?

The way tungsten carbide is made is so interesting. Tungsten, carbon and other elements like cobalt or nickel are ground into a powder. They are compressed with high-pressure dyes to form a round blank (for rings). The blank is then fired in an oxygen free furnace at 2400 degrees Fahrenheit to form an extraordinarily hard ring. Rings are then cut and shaped using diamond tools with approximately 30 steps required for completion. The cutting and shaping of a tungsten carbide ring is similar in many ways to the cutting and polishing of a rough diamond. The rings can then be inlaid with gold, silver, platinum, Mokume, or Shakudo. The inlay is created by grinding a channel in the center of the ring and compressing the metal into it under extreme pressure. The ring is then polished with diamond polishing tools and wheels. This creates a permanent luster and polish that is not possible with other metals.

There are many different kinds of tungsten carbide jewelry. Tungsten carbide can be changed significantly within the carbide manufacturers sphere of influence, determined by grain size, cobalt content, dotation and carbon content. Some people have shown an allergy to cobalt. Thus, many of the tungsten carbide Jewelry manufacturers have cobalt free jewelry replacing the cobalt with nickel.

So why Tungsten Carbide?

Tungsten Carbide is the only rare and exotic metal that can promise a permanence in polish and finish that will endure as long a the wearer bears it. Rings made from gold, platinum, and even titanium all become significantly less attractive over time. The patterns and design in many gold rings will all but disappear after several years. For me, it didn't take several, but two years for the brushed finish on my gold wedding band to rub off. I take it back and get it re-brushed every few years so that it looks like it did when my wife gave it to me.

Tungsten carbide jewelers are able to guarantee that their ring's shine for life. The reason why? The chance of it ever getting scratched or dulled is extremely low. Tungsten Carbide rings will and do maintain a lasting, beautiful, shiny finish. To the wearer tungsten carbide jewelry speaks of commitment and security to the couples who choose Tungsten Carbide for their wedding bands due to it everlasting nature.

What Mokume Gane and Shakudo? I mentioned a few inlays commonly used in Tungsten Carbide rings, Mokume Gane and Shakudo. These two inlays are really the same thing just with different metals used in the manufacturing process. Mokume Gane (moh-ku-may Gah-nay) is ancient Japanese metalworking developed in feudal Japan by master sword smiths. This is a technically difficult and time-consuming process. The process begins by stacking layers of different colored metals and heating them to 1400 degrees under extreme pressure for 10 hours. This allows the atom from gold and other metals to fuse together, forming distinctive patterns. The metal is then forged and rolled to set the crystal structure. Finally the Gold and other metal ate manipulated by twisting and curving to expose the multiple layer, thereby forming unique ring patterns. No Mokume Gane or Shakudo rings will look alike!

Mokume is usually made with white Palladium and either silver or 18k green gold. Shakudo usually has 90-95% copper and 5-10% pure gold, layered with either sterling silver or 14k yellow Gold. Shakudo tends to have a darker and more deliberate pattern than Mokume. However, both of them are equally gorgeous!
 
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Tungsten(VI) oxide, also known as tungsten trioxide or tungstic anhydride, WO3, is a chemical compound containing oxygen and the transition metal tungsten. It is obtained as an intermediate in the recovery of tungsten from its minerals.Tungsten ores are treated with alkalis to produce WO3. Further reaction with carbon or hydrogen gas reduces tungsten trioxide to the pure metal.

    2 WO3 + 3 C + heat → 2 W + 3 CO2
    WO3 + 3 H2 + heat → W + 3 H2O

Tungsten(VI) oxide occurs naturally in form of hydrates, which include minerals: tungstite WO3·H2O, meymacite WO3·2H2O and hydrotungstite (of same composition as meymacite, however sometimes written as H2WO4). These minerals are rare to very rare secondary tungsten minerals.

History
Tungsten has a rich history dating back to its discovery during the 18th century. Peter Woulfe was the first to recognize a new element in the naturally occurring mineral, wolframite. Tungsten was originally known as wolfram, explaining the choice of "W" for its elemental symbol. Swedish chemist Carl Wilhelm Scheele contributed to its discovery as well with his studies on the mineral scheelite.

In 1841, a chemist named Robert Oxland gave the first procedures for preparing tungsten trioxide and sodium tungstate. He was granted patents for his work soon after, and is considered to be the founder of systematic tungsten chemistry.

Preparation
Tungsten trioxide can be prepared in several different ways. CaWO4, or scheelite, is allowed to react with HCl to produce tungstic acid, which decomposes to WO3 and water at high temperatures.

    CaWO4 + 2 HCl → CaCl2 + H2WO4
    H2WO4 + heat → H2O + WO3

Another common way to synthesize WO3 is by calcination of ammonium paratungstate (APT) under oxidizing conditions:

    (NH4)10[H2W12O42]•4H2O → 12 WO3 + 10 NH3 + 11 H2O

Structure
The crystal structure of tungsten trioxide is temperature dependent. It is tetragonal at temperatures above 740 °C, orthorhombic from 330 to 740 °C, monoclinic from 17 to 330 °C, and triclinic from -50 to 17 °C. The most common structure of WO3 is monoclinic with space group P21/n.

Uses
Tungsten trioxide is used for many purposes in everyday life. It is frequently used in industry to manufacture tungstates for x-ray screen phosphors, for fireproofing fabrics and in gas sensors. Due to its rich yellow color, WO3 is also used as a pigment in ceramics and paints.

In recent years, tungsten trioxide has been employed in the production of electrochromic windows, or smart windows. These windows are electrically switchable glass that change light transmission properties with an applied voltage. This allows the user to tint their windows, changing the amount of heat or light passing through.

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Wedding bands are traditionally created out of gold of varying purities. Platinum has often been an alternative, albeit a more costly one due to the difficulty in working with the metal, while silver has also been an alternative but not as favorable due to the softness of the metal. Another alternative wedding band material that has emerged is tungsten, but one must consider the pros and cons of this metal before choosing it for a wedding band.

Durability
Tungsten wedding bands are very strong and show a resistance to bending that gold, silver, platinum and titanium can not come close to attaining.

Tungsten rings actually do not bend under pressure, instead it takes an extreme amount of pressure to shatter them. For this reason this metal is viewed favorably by those who perform manual labor since the rings do not wear during heavy loads. Scratch resistance is another advantage for tungsten rings as it takes a material with an abrasion capacity near that of a diamond to put a scratch in tungsten.

Resizing
Since wedding bands are intended to be items with a lifetime usable capacity, it is important to be able to re-size these rings as a person's weight can fluctuate throughout his life. It is nearly impossible to re-size a tungsten wedding band which is a disadvantage of the material for this application.

Engraving
Many people elect to have a special sentiment or date engraved on the inside of their wedding band to solidify the sentimental nature of the item. Due to the strength of tungsten engraving is not optional. A jeweler can attempt to engrave the band but these markings will be faint at best.

Maintenance
Tungsten is a popular choice for wedding bands as the metal does not require polishing to keep its original luster. Oils from the skin and outside chemicals do not have an effect on tungsten's sheen so it is a popular choice for those who desire a low maintenance band.

Allergic Reactions
Some jewelers use cobalt in the tungsten alloy for their bands. Many people are allergic to cobalt and experience rashes as a result of exposure. To negate the risk of this happening it is advised to buy a tungsten wedding band that uses nickel in its alloy composition. When nickel is used in tungsten alloys it actually becomes hypoallergenic, even to those who suffer from nickel allergies.

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Tungsten carbide (WC)
Tungsten carbides are divided into two categories. The first is the cemented tungsten carbides, also called hard metals, which are essentially WC produced from sintering a mixture of carbon black and hydrogen-reduced tungsten powder at 1,500° C (2,700° F). These are cemented using a cobalt or nickel binder, with or without other refractory carbides. The major uses of cemented carbides are for cutting and drilling tools, forming and drawing dies, and tire studs.

The second group is called fused or cast carbide, consisting of W2C and a eutectic mixture of WC and W2C. Harder but more brittle than the cemented carbide, it is used in wear-resisting applications such as anvils, guide sleeves in machines, and teeth and jaws for excavators.

Other compounds
Tungsten bronze, composed of tungstates of the alkali and alkaline-earth metals, is employed as a substitute for bronze in ornamental paints. Sodium tungstate is also used to produce phosphotungstic acid-type organic dyes and pigments, which are brilliant, light-resistant, and insoluble in water and linseed oil. Calcium and magnesium tungstates are used as phosphors in fluorescent light and television tubes. Ammonium tungstate and other compounds are used as catalysts in the petroleum industry for hydrotreating, hydrocracking, and polymerization.

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