Blu-spec CD describes a Red Book Compact Disc manufactured by a proprietary process introduced by Sony Music Entertainment Japan in late 2008. Its name derives from the similar manufacturing process to that used to create Blu-ray Discs. Instead of a traditional infra-red laser, a blue laser is used for recording the pits on the CD master that is needed for disc replication. The blue laser creates more precise pits, which Sony claims reduces distortion in the optical read-out process.
On 28 September 2012, Sony Music Entertainment Japan announced "Blu-spec CD2" or BSCD2, a progression of the Blu-spec CD format which employs a more precise BDcutting machine, a master disc that is made from the same smooth material as silicon wafers for chip manufacture, and a different recording layer material for the master disc. Sony refers to this process as "Phase Transition Mastering".
A Blu-spec CD can be played on all CD players and does not require a blue laser to be read. The same holds true for Blu-spec CD2 discs.