Emeralds are the birthstone for May, the month of spring time and romance. The perfect emblem of an enduring love for marriage anniversary. The rich green color of emerald is the color of spring, and it was prized as the gemstone symbolizing love and rebirth.
Emerald is a form of Beryl and its characteristics emerald green color comes from traces of chromium in the crystal matrix. The better quality emerald that exceeds one carat are valued above diamonds.
Inclusions are typical in emeralds and color saturation and hue are bigger factor in determining the value of an Emerald.
The hue, color, of emeralds range from yellowish green to bluish green, with most emeralds having a very slightly bluish green color. This color is very distinct and known as, emerald green color. The tone, lightness or darkness, of this color can range from very light to very dark. The clarity of emeralds can range from transparent to opaque. The opaque emeralds are not considered to be of gem quality.
Emeralds exhibit double refraction, meaning the light is refracted in two different pattern. This often causes the emerald to exhibit two different distinct color patterns, usually being green a primary body color with a bluish green secondary color, which adds to the visual beauty of the emerald. This phenomenon, present in gemstones that measurable birefringence, meaning double refraction, is known as pleochroism. Pleochroism is the ability of a gemstone to present two or more distinctly different colors in visual observation.
Refractive index is a means of measuring how the emerald bends light. Since there are two natural refraction in a emerald, the refractive index is reported as two values. The first is approximately 1.577 ( range is +/- 0.017) and the second value is approximately 1.583 (range is +/- 0.017). The difference of these two values, known as the birefringence, is 0.006 and can be in the range of 0.005 and 0.009.
Color and clarity dominate the value determination of emeralds.
All emeralds have inclusions. These inclusion are characteristics unique to the formation of emeralds and actually aid in identification of natural emeralds and separation from created synthetic emeralds. These include faceted pyrite crystals, calcite jardin, spindle shaped cavities, and three phase inclusions with gas bubbles contained in microscopic liquid filled cavities within the crystal. Unlike other gemstones, these characteristic inclusions do not detract appreciably from the value of the emeralds unless they are distracting or adversely impact the brilliance of the gemstone. Inclusions that are distracting and diminish the brilliance of the emerald will greatly reduce the value of the gemstone.
The more intense the color of a emerald, the greater its value. The key to the effect of color on emerald valuations is color purity and intensity, regardless of source of location.
Cut and carat weight have a decidedly secondary effect on emerald values. Large faceted emeralds, over 10 carats, are readily available. One may have to settle for lighter tones, less intense color or reduced brilliance. The same can not be said for diamonds, rubies and sapphires. However, very fine emerald over one carat are very rare and with respect for value may rival and exceed that of diamonds of equal carat weight and grading.
Ruby is the birth stone for July.
Ruby is a variety of the mineral Corundum. A rubies a sapphire of red color. It extremely hard and durable gemstone, well suited for all jewelry items.
Fine quality rubies are highly prized, and in larger sizes are valued above all other gemstones, including diamonds. A ruby over two carats is extremely rare and valuable. Generally, rubies with true red color are valued above those that are darker, with purple hue. The most expensive ruby color is a deep pure, vivid red.
Rubies are heated to enhance color. The treatment is stable and permanent.
Cutting styles for ruby include mixed cut ovals or antique cushions
Rubies that are perfectly transparent, with no tiny flaws, are more valuable than those with inclusions which are visible to the eye. A well cut stone should reflect back light evenly across the surface without a dark or washed out area in the center that can result from a stone that is too Deep or shallow. The shape should be symmetrical and there should not be any nicks or scratches in the polish..
Sapphire, Gems of the Heavens
Sapphire is found in all colors of heavens; from midnight blue to the bright blue of noon sky in the Mediterranean, golden sunrise to firey reddish orange sunsets, and the delicate violet of twilight. The most valuable sapphires are a rich intense blue, a truly royal blue.
Since sapphire symbolizes sincerity and faithfulness, it is an excellent choice for an engagement ring. Sapphire is also the birth stone for September, the month when the most babies are born.
Sapphire are most often cut in a cushion shape, a rounded rectangle, or an oval shape. It can also be found in smaller round brilliant cuts and a wide variety of fancy shapes, such as triangles, squares, emerald cuts, marquises, pear shapes, and baguette shapes.
Sapphire have becomes more available, because some light, cloudy, or over dark sapphire can now be heated at very high temperatures to improve the color or clarity. This process, which dissolves trace elements already present in the sapphire, is completely stable. There is no price difference between heated or non heated stones except for the very high quality sapphires. Country of origin can also make a difference in the value of a sapphire.
The most valuable sapphires have a medium intense, vivid blue color. The best hold the brightness of their color under all different types of lighting. Any black, gray, or green overtones mixed in with the blue will reduce a stone’s value. More lighter blue is less preferred than a vivid blue , but would be priced higher than an over dark black looking blue color stone. Sapphires which are clean and have few visible inclusion or tiny flaws are the most valuable.
Sapphire is the most toughest and durable gemstone available. A sapphire is harder than any other gemstone except diamond, and it has no cleavage plane, so it can not be cut with a single blow like a diamond.
Sapphire is often considered to be synonymous with the color blue. However, sapphire is beautiful beyond blue, in every color except red, because red is called ruby. The other colors of sapphire can be as beautiful and rare, but they are usually priced less. Yellow, orange, lavender, and other pastel shades are very affordable.
Tanzanite is relatively new. This transparent blue gem first turned up in 1962 in northern Tanzania, in eastern Africa. Scientists identified it as a Variety of the mineral zoisite. Tanzanites have grown in popularity steadily over past years.
Tanzanite are heated to produce colors that include light to dark violetish blue and bluish purple, as well as pure blue. Rich, deep hues are valued most and are seen in stones weighting 5 carats or more. Tanzanite typically shows strong pleochroism, which means it displays different colors from different directions. It usually look violetish blue from some directions, purplish from others.
Blue tanzanite is generally worth more per carat, but because of the way tanzanite crystal grow, a cutter can usually get bigger stone by orienting the gem to show the purple color. While the trade considers the pure blue stones to be the top grade, some customers actually prefer the lighter and more purplish colors.
Sudden changes in temperature may cause cracking in tanzanite. The gem is stable to light, and can be attacked by hydrochloric and hydrofluoric acid.
Tanzanite is routinely heat treated to produce tanzanite color in transparent brownish material. This treatment is undetectable, but assumed because of its prevalence.
Tanzanite should cleaned using warm, soapy water. Ultrasonic cleaners and steam cleaners should never be used.
For gemstones and gemstones jewelry cleaning and care, please refer to the “Jewelry Care Gallery”