Research the price of the CD when purchased new online or in a music store. If the CD that is being sold is offered at a very low price, it is an indication that it hasn't cost the seller much likely is a disc that has been copied illegally.
Turn the CD over, and look at the color of the back. Most professionally made CDs have a silver back that contains factory-stamped information. Re-writable CDs have a burnable layer, which generally results in a green or purple coloration to the underside of the disc.
Look at the label on the front of the CD. Many labels on authentic music CDs are stamped on, and the design is imprinted directly onto the disc. Feel the front of the disc. Authentic CDs may have raised sections where the design has been printed. Illegally copied discs often have inexpensive labeling, such as inkjet printing or a handwritten album title.
Examine the CD case. Most professional CDs come in plastic jewel cases, but some have cardboard boxes. Find the album in a music store or on the Internet to determine which type of case it should have. Counterfeit CD producers are more likely to use a jewel case, because these are inexpensive. The front of illegal CD cases usually has a black rectangular column on the left-hand side. Older professional CDs may have this black bar, but modern CDs ordinarily use see-through plastic.
Pull out the album insert. Most authentic CD albums come packaged with a small booklet that contains the copyright information and other liner notes. Liner notes are too expensive for a counterfeit CD producer to make, so they usually print off the front cover of the album. If your CD has no liner notes, use that in conjunction with the other factors listed to determine whether the CD is genuine.