ENCYCLOPEDIA
BLUE SAPPHIRE FULL GUIDE
CHARACTERISTICS OF BLUE SAPPHIRE
Etymology: Derived from the Greek "sappheiros," indicating a blue gem.
Family: Belongs to the Corundum group.
Composition: Primarily Aluminum Oxide, with iron and titanium as color-inducing trace elements.
Hardness: Exhibits a high hardness of 9 on the Mohs scale, indicative of its excellent durability.
Density: Has an approximate density range of 3.95 to 4.03, typical for sapphires.
Optical Properties: Shows uniaxial optical character with a refractive index ranging from 1.762 to 1.770, contributing to its brilliance.
Birefringence: Features a low birefringence of about 0.008, often imperceptible without specialized equipment.
Crystal System: Forms in a trigonal crystal system, common among corundum varieties.
THE ORIGIN OF BLUE SAPPHIRE
The origin of blue sapphires is deeply connected to their geological formation, which occurs in certain types of metamorphic and igneous rocks under high temperature and pressure conditions deep within the Earth's crust. These conditions allow for the growth of corundum crystals, the mineral from which sapphires are formed. The blue color in sapphires is primarily due to the presence of trace amounts of elements such as iron and titanium.
Some of the most notable sources include:
- Sri Lanka
- Kashmir
- Thailand
- Madagascar
- Montana
- Australia
- Burma
CARAT
For blue sapphires, the carat weight, where one carat equals 0.2 grams, is a key factor in determining the gemstone's value. The larger and higher quality the blue sapphire, the more scarce and consequently, more valuable it becomes. It's important to distinguish between "carats," a measure of weight for gemstones like blue sapphires, and "karats," a unit indicating the purity of gold.
THE COLOR OF BLUE SAPPHIRE
The color of blue sapphires is one of their most defining and valued characteristics. It ranges from pale, sky blue to deep, rich royal and navy blues. The most prized sapphires exhibit a vibrant, medium to deep cornflower blue, often referred to as "Ceylon Blue" after the traditional source in Sri Lanka.
The geographical origin of a blue sapphire can significantly influence its color. For instance:
Kashmir sapphires are renowned for their velvety, true blue color with a slight violet hue.
Sri Lankan (Ceylon) sapphires often have lighter, vibrant blues.
Burmese sapphires tend to display a deeper, intense blue.
Australian sapphires are known for darker hues, sometimes with a greenish tint.
Madagascar sapphires can vary widely, offering a range from pastel to rich royal blues.
HUE
This refers to the gemstone's basic color. In blue sapphires, the ideal hue is a pure, vivid blue without any green or gray overtones.
SATURATION
Saturation indicates the intensity or purity of the hue. High saturation in blue sapphires means the color appears more vivid and rich, enhancing the gemstone's beauty and value.
TONE
Tone describes the lightness or darkness of the color, ranging from very light to very dark. The most valued blue sapphires have a medium to medium-dark tone, striking a balance that maximizes the stone's overall appeal.
THE CLARITY OF BLUE SAPPHIRE
Clarity in blue sapphires refers to the presence of internal features known as inclusions and external characteristics called blemishes. Clarity can significantly impact a sapphire's value, but it's important to note that because sapphires are colored gemstones, the clarity standards are not as stringent as those for diamonds.
CUTS & SHAPES
The shape of a blue sapphire refers to its overall form or outline when viewed from above. The choice of shape is largely a matter of personal preference, but it can also influence the perceived size and brilliance of the stone.
The cut and shape of a blue sapphire not only define its appearance but can also significantly impact its value and suitability for various types of jewelry. A well-chosen cut and shape can enhance the natural beauty of the sapphire, making it a stunning centerpiece for any piece of jewelry.
OVAL BLUE SAPPHIRE
ROUND BLUE SAPPHIRE
PEAR BLUE SAPPHIRE
CUSHION BLUE SAPPHIRE
CALENDAR
Blue sapphire is the birthstone for September. It is traditionally associated with qualities such as wisdom, loyalty, and nobility, making it a meaningful gift for those born in that month.
Blue sapphire is traditionally associated with the 45th wedding anniversary. It symbolizes long-lasting love and commitment, making it a meaningful gift to celebrate 45 years of marriage.
FAMOUS BLUE SAPPHIRES
The Star of India
One of the largest gem-quality blue star sapphires in the world, weighing 563 carats. Its unique feature is the star-like phenomenon known as asterism, visible on both sides of the stone due to its double cabochon cut. It's housed in the American Museum of Natural History in New York.
The Logan Sapphire
The Logan Sapphire, weighing approximately 422.99 carats, is one of the largest faceted blue sapphires and is known for its deep blue color. It is currently displayed at the National Museum of Natural History in Washington, D.C.
The Kashmir Sapphire
Sapphires from the Kashmir region are known for their exceptional quality and cornflower blue color. Although not a single stone, Kashmir sapphires in general hold a legendary status among gem enthusiasts.
The Blue Belle of Asia
This 392-carat sapphire is one of the most famous sapphires in the world, known for its vibrant cornflower blue color. It was discovered in Sri Lanka in 1926 and has a storied history, including being auctioned for a record price at Christie's in Geneva.
TREATMENT
Blue sapphire treatment refers to various processes applied to enhance the color, clarity, or overall appearance of the gemstones. The most common treatment for blue sapphires is heat treatment, although other methods exist. Understanding these treatments is crucial for consumers and collectors alike, as they can significantly affect the value and durability of the sapphires.