December

Most blue topazes come out of the earth colorless or pale blue. A two-step heat and radiation laboratory treatment is then used to turn these stones vivid greenish blue. Blue topazes are not only beautiful but inexpensive.

Through the ages, topaz has been popularly associated with wealth. This is likely due to its more common yellow color, which led some to believe that topaz had the mystical ability to attract gold.

Blue topaz are refered to by trade names such as “London Blue,” “Swiss Blue,” and “Sky Blue.” London Blues have a dark steel blue or grayish blue color. Swiss Blues show a highly saturated greenish blue. Sky Blues show pale blue colors and may somewhat resemble aquamarines in hue and tone.

Found in Tanzania, tanzanite can show intense blue and violet hues after heat treatment. It can mimic fine sapphire at a fraction of the price but requires a protective setting.

Tanzanite is believed by some to facilitate a higher consciousness, intuition, and perception. Its blue color is also thought to bring calmness to the wearer.

Blue and violet tanzanites can also exhibit a slight color shift, depending on the light source.

Don’t be confused by the name. Zircon is a natural, magnificent, and underrated gemstone that has been worn and treasured since ancient times. It’s not cubic zirconia. Zircons come in many colors, but blue is the most highly prized. Blue zircon has become a modern December birthstone.

Due to the fact that blue colors are generally considered a soothing and spiritual color, it comes as no surprise that blue zircons are associated with serenity and purity.

Blue zircon displays a light yet saturated color. Most blue zircon has been exposed to heat treatment to maximize its appearance.

Chemically, turquoise is a hydrated copper/aluminum phosphate of aggregate, cryptocrystalline structure. Only one deposit is known to produce transparent to translucent crystals: Lynch Station, Virginia. (Specimens from this locale are rare and bring a hefty price from collectors). More typically, this stone occurs as an opaque deposit in nodules, in veins within host rocks, or as shallow crusts on the surface of rocks. Massive turquoise is always opaque.

In terms of value, color evenness and saturation are the primary considerations. A turquoise’s capacity for taking a good polish without stabilization is also an important factor. (See “Are Turquoises Enhanced” below and our article on turquoise treatments for more information).

Generally, darker shades and less green tint in blue colors add more value to turquoises. Of course, consumers who appreciate matrix patterns would consider their beauty crucial to determining their value. Spiderweb turquoise, veined with black matrix in a pattern that looks like crocheted lace, is quite popular. Other matrix pattern varieties also have their devotees.

Colors range from shades of blue to blue-green to yellowish green depending on the elements present. Copper forms part of a turquoise’s chemical structure and adds blue color. However, traces of chromium and vanadium add green. Iron traces adds yellow. There are also rare specimens of blue-violet color that contain strontium impurities. In general, US mines produce slightly greenish blue to green gems due to high iron and vanadium content.

Lapis lazuli has been used since ancient times and remains popular today. This gemstone has been prized for its bright, blue color and used for inlay and intarsia as well as for pigments for cosmetics and paintings. Its contrast and eye appeal is irresistible. Today, jewelry is its predominant use.

Lapis lazuli value is determined almost exclusively by color. A deep, intense, blue with violet tones would be at the apex. Fine grained, uniform specimens can attain a smooth, highly polished surface not seen in lower grades.

The colors of lapis range from a medium, grayish blue to intense, royal blue, to deep indigo, with varying amounts of white and brassy gold from calcite and pyrite inclusions. Some purists desire a specimen that’s almost entirely lazurite, a deep and uniform blue, but most seek a piece with a moderate to generous sprinkling of golden-colored pyrite.