Sapphire (sapphire)

Category: Oxide
Mineralogy Name: Corundum
Chemical Composition: Alumina
Chemical Formula: Al2O3
Crystal System: Trilateral Crystal System
Refractive Index: 1.762~ 1.770
Birefringence Index: 0.008~ 0.010
Dispersion Value: 0.018
Specific gravity: 3.95~ 4.03
Mohs Hardness: 9
Color: Other colors except red (i.e. ruby)
Origin: Thailand, China, Myanmar, Laos, Cambodia, India Kashmir, Madagascar, Sri Lanka, Australia

The English name of sapphire is "Sapphire", derived from the Greek "Sappheiros", which means "blue stone". Sapphire is a general term for corundum gems in other colors except ruby. Sapphire can appear pure blue, or it can range from greenish blue to indigo blue.

The reason why sapphires show color is because they contain titanium (Ti) and iron (Fe) elements inside. And color is an important factor affecting the value of sapphires. Generally speaking, the thicker the color and the absence of obvious color ribbon, the higher the value of sapphires.

Colored Sapphire (Fancy Sapphire)

It is a variant of corundum, whose main component is alumina (Al2O3). In its purest state, corundum is colorless, but pure colorless corundum is very rare. Most corundum contains trace amounts of other elements, and the interaction between these elements will produce different colors, which directly determines the hue of the gemstone, while the content of the elements determines the saturation of the hue.

When corundum contains trace amounts of chromium (Cr) elements, it appears red, which is ruby; when it contains trace amounts of iron (Fe) and titanium (Ti) elements, it appears blue; when it contains elements such as iron (Fe) and nickel (Ni), it appears yellow.

Therefore, in the corundum series, in addition to blue sapphires and rubies, there are also colored sapphires (Fancy Sapphire), which present a variety of colorful colors, such as green, yellow, orange, pink, purple, black, brown, etc., and even multiple colors may exist at the same time on the same gem. Corundum of these colors usually describes its name by color, such as yellow sapphire, green sapphire, etc. In the jewelry industry, when professionals use the word "Sapphire" alone, it usually refers to "blue sapphire."

Colored sapphires are usually rarer than blue sapphires, and some of these colors are very rare, especially colored sapphires with large carats.

The Legend of Sapphire

The legend of the sapphire was fascinating. It was said that Richard Burton, the famous 19th century explorer and author of "The Arabian Nights," owned a huge starlight sapphire and regarded it as a talisman that would always bring good luck no matter where he was. According to legend, with just one look at the sapphire, what he wanted in his heart would be fulfilled.

There is also a legend about a young man named Banda. He was brave and upright. In the struggle to maintain the peace of the people, he turned himself into a huge flying arrow and stabbed deeply into the Demon King's throat. The vicious Demon King struggled uncontrollably before he died and crashed a corner of the sky, causing stars to fall one after another. Some of the stars that were stained by the Demon King's blood turned into starlight rubies, while the stars that were not stained with blood turned into starlight sapphires.

The ancient Persians believed that the earth where humans lived was supported by a huge sapphire, and that the reason why the sky was blue was because of the brilliance reflected by the sapphire. These legends brought infinite reverie and imagination to people, making the sapphire full of mysterious and magical colors.

The quality of sapphire

The quality factors of sapphires affect their value and beauty. You can view 4c

Color (Color) Sapphires can appear in a variety of colors, including pink, orange, yellow, green, and purple. No matter which color it is, the more saturated and uniform the color, the higher the value of sapphires. Color is one of the most important factors that affect the value of sapphires, and high-quality sapphires should have a rich and bright hue.

Clarity

Sapphires usually contain some contents, but their clarity is usually higher than rubies. Sapphires with high transparency are very rare and have high value.

Cut The color distribution of sapphires tends to be uneven, showing a color ribbon-like phenomenon called color ribbon (Color Zoning). During the cutting process, the gemstone cutter adjusts the cut of the gemstone to focus the color in one area to show the best visible color and retain the original weight of the gemstone as much as possible. Excellent cutting can enhance the beauty of sapphires.

Carat sapphires of large commercial value were relatively rare. The larger the carat number, the higher the price. The carat number of sapphires ranged from a few minutes to a few hundred carats. Generally speaking, it was easier to obtain sapphires with large carats than rubies.

The quality elements of sapphires influence each other, and a high-quality sapphire can only be evaluated after comprehensive consideration. Everyone's preferences for sapphires are also different, so when choosing gems, they can choose according to their own preferences and needs.

Star Sapphire

A gemstone with a starlight effect. Under the irradiation of parallel light, two, three, or six intersecting banded structures will appear on the surface of some gemstones that have been cut in an arc shape, forming four, six, or twelve intersecting star lines (of which six rays are the most common), like twinkling stars in the night sky. This effect is called Asterism. At this time, a silk-like texture appears on the surface of the gemstone, which is very charming.

The starlight effect is like a special blessing given to gemstones by nature, and when this starlight appears in sapphires, it is even rarer, mysterious, and beautiful. The formation of the starlight effect mainly depends on the silk-like inclusions inside the gemstone, but they may affect the clarity of the gemstone. Therefore, only a few high-quality gemstones can have transparency, high color, and starlight effect at the same time.

The ideal starlight sapphire should have the intersection of starlines at the center of the gem, complete, bright, continuous, neat, and uniform in intensity. When the light shifts or shakes the gem, the starlight effect will smoothly and flexibly slide across the surface, giving people a wonderful feeling.

Color-changing sapphire

In addition to ordinary sapphires, there is also a rare natural gemstone called "color-changing sapphire." This kind of gemstone will show different colors under different light sources, which is very precious and rare. The color-changing effect is caused by the vanadium and chromium elements inside the sapphire, causing the gemstone to change color under different light. However, these two chemical elements must reach a certain proportion to produce a color-changing effect, so color-changing sapphires are even more rare.

Under fluorescent or LED light sources, the basic color range of typical color-changing sapphires ranges from blue to purple; while under incandescent lamps (light bulbs or candle lights), the color range is adjusted from purple to rich purplish red. This color change gives people a magical feeling, and color-changing sapphires are highly sought after because of their unique color-changing properties.

Optimized processing of sapphire

Sapphires often undergo different optimization processes to improve their appearance and characteristics.

Heat treatment is one of the most common optimization methods. By exposing the gemstone to high temperatures, the color and clarity of the sapphire can be changed. Heat treatment can enhance or even stimulate the blue hue of the sapphire. In addition, heat treatment can also remove the filamentous inclusions inside the gemstone and improve the transparency of the gemstone. Heating can also make the filamentous wrapping body newly crystallized, making its features more prominent, allowing the gemstone to exhibit a more shining starlight (starlight effect).

Diffusion treatment was another common optimization treatment. To put it simply, diffusion treatment was to allow certain elements to seep into the crystal lattice of a gemstone through high temperatures, thus changing or enhancing its color.

Irradiation treatment is less used in sapphires. This method is to expose sapphires to artificial sources of radiation to change their color. Sometimes this step is performed after heat treatment to further change the color. This process is also called "combination treatment."

These optimized treatment methods can improve the appearance and market acceptance of the sapphire, but one should pay attention to whether it has been treated or not when buying, and learn from a professional about the extent and impact of the treatment.

The price of the sapphire

We are often asked by friends who have just come into contact with colored gems, how much is a carat of sapphire, and how much is the carat price? This kind of question is usually difficult to answer, because we know that the quality of sapphire is also mentioned earlier. The quality of sapphire is mainly affected by four factors: weight, color, clarity, and cutting. Therefore, the price of each sapphire is of course not uniform. In terms of weight, the price of 1 carat, 1.5 carat, and 2 carats is different. In addition, the premium space for sapphire above 3 carats is also higher. In terms of color, the price of blue sapphire is higher. Usually blue, pink, purple, green, yellow, and white are sorted in this way. But this is not entirely the case. Because the color has the influence of saturation and brightness.

The same weight, the same color, and cleanliness will also have a great impact. From the perspective of cutting workers, Asher cut, round cut, and Redian cut are better than fire color, and this cutting method itself has already sacrificed the weight of the original stone.

Therefore, the price of sapphire is not fixed. It may be as small as a few hundred dollars or as large as tens of thousands of dollars. It is also difficult to define it with a unified line. Even affected by market supply and demand, the price of sapphire will still rise in 2024. As for how high it will rise, let's see.