Sapphire

Sapphire Basics and Characteristics

• Sapphire is a variety of corundum, consisting of aluminum oxide with trace elements.
• It is typically blue, but can also occur in yellow, purple, orange, and green colors.
• Red corundum stones are called rubies, not sapphires.
• Natural sapphires are cut and polished into gemstones for jewelry.
• They can also be created synthetically for industrial or decorative purposes.
• Sapphires in colors other than blue are called fancy sapphires.
• Fancy sapphires can be found in yellow, orange, green, brown, purple, violet, and other hues.
• Blue sapphires are evaluated based on the purity of their blue hue.
• The highest prices are paid for pure blue sapphires with vivid saturation.

Different Types of Sapphires

• Blue sapphire exists in various mixtures of primary and secondary hues.
• Violet and green are common secondary hues found in blue sapphires.
• Gems with pure blue hue and vivid saturation command higher prices.
• Parti sapphires exhibit two or more colors within a single stone.
• Parti sapphires are not commonly used in mainstream jewelry.
• Pink sapphires occur in shades from light to dark pink.
• The deeper the pink color, the higher their value.
• Star sapphires exhibit a phenomenon called asterism, which creates a star-like pattern on the surface of the stone.
• Color-change sapphires exhibit different colors in different lighting conditions.

Sapphire Treatments and Enhancements

• Sapphires can be treated by heating them to enhance their appearance.
• Other treatments include diffusion and beryllium treatment.
• Lattice diffusion treatments add impurities to enhance color.
• Disclosure of enhancements is required by the United States Federal Trade Commission.

Sapphire Mining and Origins

• Sapphires are mined from alluvial deposits or underground workings.
• Commercial mining locations include Afghanistan, Australia, Myanmar, etc.
• Classic metamorphic sapphires from Kashmir, Burma, and Sri Lanka are highly valued.
• Madagascar is the world leader in sapphire production, followed by Australia.
• Kashmir-origin sapphires have a superior vivid blue hue.

Synthetic Sapphire and Applications

• Synthetic sapphire can be produced using the Verneuil process.
• Synthetic sapphire has various industrial applications.
• It is used in watch crystals, optical windows, and electronics.
• Synthetic sapphire is chemically identical to natural sapphire.
• Synthetic sapphire is often more affordable than natural sapphire.
• Sapphire windows have a wide optical transmission band.
• Sapphire wafers are used in the semiconductor industry for devices based on gallium nitride.

Sapphire Data Sources