Dave's Blog

December's Birthstones

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Zircon

Many people do not even know that there is an exceptionally brilliant natural gemstone called zircon. Zircons name alone is often confused with the laboratory-grown imitation diamond known as cubic zirconia. To make matters worse for many years the colorless variety of zircon was itself popular as an imitation diamond because of its natural brilliance. The sky blue variety of zircon has modest recognition as a December birthstone but also occurs in green, dark red, yellow, and orange, brown, colorless and in rare instances a bright blue. Zircons range of colors, its limited availability and reasonable cost make it a favorite with collectors.

Zircon was known to the ancients and its name most likely comes from the word “zargun” which is Persian for “gold colored”. The Kalpa Tree in Hindu poems had leaves of zircon and gemstone fruit and was a great gift to the gods. In the Middle Ages zircon was said to promote sleep, bring honor and wisdom and prosperity to the owner. Sadly, even though zircon is one of nature’s most brilliant gemstones, it has been historically overlooked only being used when other, better-known gems where unavailable.

Major sources for zircon are Sir Lanka and Burma other sources include Thailand, Myanmar, and Australia.
Zircon is almost always heat treated. The heat treatment is fairly stable, but in some instances, a treated zircon will revert wholly or partially to its original color. Even though zircon is a fairly hard gemstone it can abrade and chip fairly easily. Zircon is relatively safe for steam or ultrasonic cleaners. Zircon can be cleaned with commercial jewelry cleaner or with mild soap and water along with an old toothbrush to clean the setting as well. Always rinse and dry your jewelry after cleaning.


Blue Topaz

Because of zircon's limited availability, blue topaz has been gaining in popularity as an alternative birthstone for December.


The history of topaz is shrouded in confusion. Ancient societies had not yet discovered scientific methods and would categorize gems according to their appearance. Any yellow gem would commonly be called a topaz. The name topaz itself has two possible sources; it could be derived from a Sanskrit word that means either yellow or fire, or it could be derived from the ancient Greek island Topazios in the Red Sea. The island Topazios was said to have many bright yellow gemstones, but because the island was covered in fog much of the time they were very difficult to find. It is now thought that the island in question is Zebargad and the gems peridot.

Topaz occurs naturally in wonderful shades of sky blue, vivid aquas to darker hues of blue and greenish blue. Blue was once the rarest of all topaz colors, but today has become the most common thanks to modern color enhancement techniques. In recent years, as topaz’s popularity grows, new treatment processes have become available creating exciting new colors. These new colors range from dark blues to reds and pinks, greens, and even topaz with rainbow iridescence.

Topaz is usually heat treated and irradiated to improve its color. Blue topaz is clear topaz that has been first treated by heat then irradiated to create various shades of blue. These treatments are very stable. The newer treatment process is a bonded surface coating and special care should be taken with these gems.

Most of today’s topaz mined and cut in Brazil, however, it is also found in Sir Lanka, Afghanistan, Russia and South Africa. Topaz is also found in Mexico and in Utah.
Topaz is a hard gem and will resist scratching and will keep its polish for years. Topaz does however easily cleave (split or crack). Because of this property care should be taken to avoid sharp blows or sudden temperature changes. Topaz should not be cleaned with steam or ultrasonic cleaners. Topaz can be cleaned with commercial jewelry cleaner or a mild soap and water along with an old toothbrush to clean the setting as well. Always rinse and dry your jewelry after cleaning.

Turquoise

Native American cultures have long revered turquoise. In ancient Mexican society, turquoise was reserved for the gods. Turquoise, however, has an even more ancient story dating back to as early as 5500BC. Egyptian royalty adorned themselves with turquoise. Turquoise was believed to have metaphysical powers that would guarantee one's health. Ancient manuscripts from India, Persia, Afghanistan, and Arabia all report that the owner of turquoises health could be determined by color variations within the stone. Turquoise was also thought to be protection from evil and would guarantee good fortune. Turquoise most likely first came to Europe in the thirteenth century from Turkish sources. The new stone was called simply “Pierre tourques”, French for Turkish Stone.


Turquoise is generally an opaque stone, but it can be translucent. Its color ranges from light to dark blue and can also be a blue-green color. The most desirable color for turquoise is an intense “robins egg” blue, as a general rule, however, the bluer the blue the more valuable the turquoise. Turquoise sometimes contains a network of veins of other materials that are often black to brown in color. These networks can often form interesting patterns throughout the stone and are called spider webs. Although turquoise that is free of these veins is considered more desirable, some prefer the patterns the spider webs make.


The most important sources for turquoise are the southwestern US, Iran, Tibet, and China. Turquoise deposits are often found along with copper and sometimes the byproduct of copper mining.


Turquoise is often permeated with plastic to improve its color. This process is stable. Turquoise can also be dyed or treated with colorless oil or wax. These are unstable treatments. Special care needs to be taken with any turquoise, treated or not, as it is a porous gem and tends to absorb anything it comes into contact with. Avoid all cosmetics, perfumes, skin oil, soaps or any other chemicals. Turquoise should never be cleaned with ultrasonic or steam cleaners. All commercial jewelry cleaners should not be used. To clean turquoise wipe it gently with a clean soft moist cloth.


Tanzanite


Not until the 20th century did tanzanite burst on to the stage and join the cast in the long and noble story gemstones. Discovered in 1967 at the feet of Mount Kilimanjaro, its only known source, tanzanite has rapidly become one of the worlds most sought-after gems. It is no wonder; the rich violetish-blue of fine tanzanite speaks of the awe-inspiring beauty of its source. The story of tanzanite is said to begin when some of the brown crystals, lying on the dry grass, where caught in a fire started by lightning. Masai cattle herders in the area noticed that the brown crystals had turned to a beautiful blue-violet color and picked them up. Introduced to the United States by Tiffany & Co., tanzanite gets its name in from the country in which it is found, Tanzania.


Tanzanite is a variety of the gemstone zoisite. When tanzanite crystals are unearthed they have a brownish to bronze hue. It is not until gentle heat is applied that the miracle happens and the vibrant, breathtaking, blue of tanzanite is realized. Tanzanite’s beauty is also enhanced by an unusual property the gem has call “pleochroism”. Pleochroism is a gem's ability to display more than one color when viewed from different directions. In one direction tanzanite may be blue, in another, it may be violet or purple, and in yet another, it may be bronze or grey. Tanzanite’s ability to display more that one color ads a depth, a unique subtle richness to its hue; which other gems cannot match. Tanzanite’s color ranges from blue to purple. In smaller sizes, tanzanite tends to be lighter shades of soft blue to violet, purple, or lavender. Tanzanite’s depth of color shows itself the best in larger sizes of about four carats and above.

The most desirable color for tanzanite is a medium-dark, deeply saturated, rich pure blue. Cutters will go to great lengths to achieve this color; even though they know they will sacrifice a great deal of weight, they know the result is so breathtaking that it will leave one speechless.

Tanzanite has only one source, the foot of Mount Kilimanjaro, in the Merelani Hills of Tanzania, eastern Africa.
Although tanzanite is a fairly hard gem it is not a particularly durable one. Tanzanite can chip and break when exposed to even moderate blows or sudden changes in temperature. Pendants and earrings are the best choices for tanzanite. When tanzanite is mounted in rings or bracelets special care should be taken when worn. Tanzanite should never be cleaned with steam or ultrasonic cleaners. Tanzanite can be cleaned with most commercial jewelry cleaners or with mild soap and water along with an old toothbrush to clean the setting as well. Always rinse and dry your jewelry after cleaning.