Archive for October, 2010

December Birthstones : Tropical Blue Sea meets the Autumn Blue Sky

Turquoise had been popular in many ancient civilizations such as those in Egypt, Persia, China, and the Americas. Europeans got to know about this then “exotic gem from the east” from the Turkish traders (hence the name) that brought them over from Persia.
Turquoise art
Turquoise gems are still widely sought after today because of their unique combination of color and opacity. It is one of the most popular non-transparent gems around. Turquoise looks good on any setting, metal or otherwise. Cabochon, beads, and other fancy shapes are the most common cuts instead of facets. Exceptionally large nuggets and blocks of turquoise can also be sculptured into various types of wearable works of art or non-wearable decorative items.
Turquoise character
Turquoise has hues that vary from blue to green or yellow green, with all the possible combinations in between. It has a sheen or luster that is typically similar to that of wax or rough glass; and it is one of the softest of gemstones, having a Mohs scale hardness rating of only 6, which is one rank below that of the common mineral quartz. Turquoise specimens are also highly porous because they are made up of millions of individual interlocking cryptocrystalline turquoise crystals. Brown, black, or gray-brown flecks or veins made up of other minerals such as pyrite are often found embedded in turquoise.
Turquoise care
Because of its softness, turquoise is usually treated either with wax or resin. Wax treatment of turquoise has been practiced since ancient times and it does not add or detract from the value of the gem since most turquoise has a natural waxy luster. Bare turquoise pieces must be periodically waxed (with beeswax or paraffin) to protect them from light, heat, perfumes, moisture, sweat, and so on. Resin treatment imparts greater durability to each individual specimen compared to waxing. Resin treatments are sometimes preceded by color-enhancing treatments; but the highest quality turquoise gems do not need to be color enhanced and as such are only treated with colorless protective resins.
Blue Topaz
In contrast to the opaque turquoise, blue topaz–the substitute modern birthstone for December–is exceedingly clear and transparent, particularly the highest-quality gem specimens. Topaz typically has the luster of diamond or glass, which also contrasts with the waxy or rough glass luster of turquoise. Naturally blue topaz is quite rare and usually has a pale blue or sky-blue tone. The purer the blue hue (little or no extraneous browns or grays), the higher the values these gems acquire.
Topaz treatments
Some blue topazes get their color from radiation and heat treatments. These treatments are acceptable as long as they are declared. Usually the darker the resultant tone (e.g., London blue), the more expensive the specimen. However, note that irradiation and heat treatments may make topaz gems more brittle thereby making them more sensitive to mechanical stress and wear. Reputable labs that treat topazes indicate the appropriate enhancement codes and gem re-fashioning warnings on their product literature.
For additional information on topazes, please see our previous article on this November birthstone.

Astral Topaz: November’s Birthstone From the Sky

From azure blue to yellow sun to orange sunset, topaz is the jewel of the sky. The pure transparency plus the vivid colors of topaz remind one of being on top of a mountain and reveling in the changing beauty of the sky.

Topaz variety

Topaz is clear and transparent when pure and it’s the impurities that give it its various shades of yellow, gold, pink, orange, red, light-purple, light-brown, green, and blue. Blue topaz has become very popular and its color ranges in tone from the very light sky blue to the mid-toned Swiss blue, and finally, to the darker-toned London blue. Pink and yellow precious topazes are particularly well sought after as they are quite rare, with some of the yellow gems exhibiting the even rarer (among topazes) cat’s eye effect. Imperial topaz shows the characteristic but varying combinations of pink, yellow, tan, orange, and red hues.

Topaz charm

Topaz legends ascribe various beneficial effects on someone wearing this gem such as better vision, greater strength, increased intelligence, higher creativity, and so on. When choosing topaz jewelry pieces, consider carefully the design of the settings, making sure that the gem is adequately protected from the jolts and knocks of daily use. Jewelry worn on parts of the body that do not often come into contact with everyday objects are the ideal pieces for setting topazes. Earrings and Necklaces, for example, are ideal mounts for topaz gems.

Topaz is harder than quartz and ranks 8 on the Mohs mineral hardness scale. Topaz is in fact the indicator mineral for that rank. Topaz also exhibits a perfect cleavage in one direction which make it less tougher than other gemstones such as beryls and sapphires. But when set properly in well-designed mounts, topaz gems can last a lifetime and can easily outshine other more well-known gems.

High-quality topaz gems have no visible blemishes (surface scratches) and few or no visible inclusions (internal “bubbles” or tiny trapped non-topaz crystals). Large topaz gems of the highest clarity (“flawless”), vivid colors, and sparkling cuts command the best prices. The pink, red, or deep-yellow colored natural topazes, especially cat’s eye topazes, are the most valuable.

Famous topaz gems

Considerable topaz gem deposits can be found in many parts of the world from the Americas to Asia, Europe, and Russia. Famous topazes include the colorless Braganza (previously mistaken for a diamond) on the Portuguese Crown, the El-Dorado Topaz (31,000 carats, yellow-brown color), and the Lua de Maraba (>25,000 carats, gray color). All of these topazes are Brazilian in origin.

Opal beauty: October’s birthstone in a class all its own

The modern birthstone associated with the month of October is opal. Opal is one of the things that Australia is famous for, and that country has the largest known deposits of this amorphous mineral. Consequently, the Australians have adopted precious opal as their national gemstone.

Opal structure

Although most opal has a non-crystalline or amorphous structure that is somewhat similar to that of glass, some opals do exhibit localized micro-crystalline structures. Viewed through a microscope, regular amorphous opal consists of tiny spheres of silica that have been stacked together in layers, with water filling the spaces between the silica spheres. Generally, the greater the micro-crystallinity of an opal specimen, the more striking its appearance becomes and the more its value increases. Other minerals that find their way into the opal structure become impurities that provide additional physical properties (color variations, for example) to an opal.

Play of color

Opals come in a wide variety of colors and color patterns; but the most valuable types, the precious opals, display different shimmering rainbow-like color “flashes” or patterns when viewed from different angles. This striking visual display of “color play” is a type of iridescence which occurs as white light passes through the layer boundaries of the silica spheres and gets diffracted into the separate wavelengths of visible radiation that comprise white light. Also, the multiple structural layers redirect or reflect these diffracted wavelengths of light in such a way that they mix or interfere with one another. The same optical phenomenon can also be observed on the plumage of some birds, on insects wings, on some snail shells, on some pearls and agates, and on soap bubbles.

Hydrated stones

Opal stones typically contain about 10% water by weight. This water is chemically bonded to the silica spheres but the bonding is weak enough that excessive exposure to heat can cause this water to evaporate. Therefore opals need to be kept away from sources of heat to prevent them from dehydration. Excessive heat can alter the color or translucence of an opal gem and can even cause the gem to crack.

Opal beauty

Numerous legends, both good and bad, have been associated with opals since ancient times; but it is the distinctive and delicate beauty of the opal that has made it desirable to many men and women throughout history. World-renowned opals include the Olympic Australis, the Andamooka Opal, the Flame Queen Opal, the Halley’s Comet Opal, the Roebling Opal, and so on. Combined with other precious gems as accents and set in silver, gold, palladium or other metals, the opal is truly a beauty to behold.

Blood Tainted Diamonds: Three Ways to Avoid Them

Conscientious customers nowadays typically inquire about the source of the diamonds they are intending or considering to purchase. “Blood diamonds” have been so named because armed factions in a number of politically unstable African states routinely coerce local populations to work the diamond mines under extreme working conditions and for very little pay.

Concerned consumers generally have three options when it comes to avoiding blood diamonds. These are: (1) buying from retailers that deal solely in diamonds mined from Canada or Australia; (2) buying a synthetic diamond; or (3) buying diamonds that have been certified by the Kimberly Process Certification Scheme (KPCS).
Conflict-free diamonds
Diamond mining operations in Canada and Australia comply with all relevant regulations and best-practices recommendations and are certainly conflict-free. The provincial government of the Northwest Territories of Canada, for example, issues its own certificates of authenticity for diamonds that have been mined within its territory and are then processed into gems at centers and labs within the province. These diamonds basically never leave the Canadian Northwest and so do not run the risk of being mixed with diamonds from other sources prior to cutting, faceting, and polishing.
Synthetic diamonds
Another way to ensure that a customer is not buying a blood diamond is by choosing a man-made diamond. Synthetic
diamonds are an alternative for those who are looking for value at a lower price. But most synthetics are limited to shades of yellow, and many of the big gem labs have refused to grade them. Without a reliable grade certificate from an established gem lab, the price of an individual synthetic might not correspond well with its actual 4Cs. The biggest drawback of synthetics is, of course, their lack of uniqueness. They come in batches, and individual gems in every batch are practically identical microscopically. The ownership of expensive synthetics can be difficult to establish, and some companies have thus resorted to techniques such as laser etching to “individualize” each gem.
Kimberly Process Certificates
Other than buying natural diamonds that had been mined and processed in Canada or Australia, the third and least reliable way for potential buyers to ensure that they purchase a non-conflict diamond is to look for a Kimberly Process Certificate. The Kimberly Process however is a voluntary system and has been criticized by some of its own originators. Partnership Africa Canada’s 2009 Diamonds and Human Security Annual Review states that the KPCS doesn’t have the teeth to enforce its prescription since legislation in participating countries is inadequate or poorly enforced, monitoring and statistical information on trades are spotty, and smuggling and non-compliance are not being effectively sanctioned. Although the Kimberly Process has received much criticism as of late, it is still the only existing system for screening rough diamonds that have not been sourced from either Canada or Australia. And since Africa is the source of approximately 65% of the world’s supply of rough diamonds, the Kimberly Process Certificate is still better than no certificate at all.

Jewelry: A Timeless Investment