There are several online shops that sell chandelier parts, including Crystal Place, ChandelierParts.com, ChandelierSupply.com and Lowe's. Many shops offer a selection of crystal chandelier prisms and pendalogues in all sorts of shapes, cuts and colors. Some shops also sell chandelier body parts such as chains, balls, cups and hardware.
When purchasing parts for a chandelier, finding a near-perfect match to the original is the main goal. While measuring crystals on the fixture, keep in mind that replacement crystals don't always include a top bead. Look for crystals that have a similar shape and size to the originals, then focus on quality. Many people don't realize that crystal parts are made in lead and non-lead varieties. Lead crystal is of the highest quality. For instance, authentic lead crystal prisms are precision-cut and often polished smooth by hand. These crystals easily reflect light by displaying a rainbow of colors. Alternatively, some lower quality crystals are pressed into shape with little to no polishing.
Restoring an antique glass chandelier is a labor of love that can be done with exquisitely cut crystals and burnished metal parts. It is even possible to find new candle covers online to replace dirty and worn ones. When replacing chandelier parts, always remember to disconnect the fixture from electricity.