When color is not specified, sapphire refers to the blue variety. Pink, yellow, white sapphire are often valued less than the blue variety of the same quality and size.
Gem quality sapphires can be easily and cheaply produced in the laboratory. The chemical compositions and physical properties are identical to the natural sapphires. The tell-tales sign of synthetic sapphires is the crystalline growth lines which are usually curved due to the pulling during the accelerated crystal growth process.
The Logan sapphire is one of the largest blue sapphire gem known. It weighs 423 carats.
See also: List of minerals