(Sorry I wasn't really able to photograph this step while doing it).
Stamp on the candle using an embossing ink. I used VersaMark. The ink will be clear but can be seen slightly by it shining in the light. If you find it frustrating to tell where your image is, this is an excellent project for tinted embossing ink like Tsukinkeo Tinted Emboss pad. You want to use a somewhat bold stamp, like this Scalloped Flourish from Lost Coast Designs. The smaller the stamp is, the easier it is to stamp on a curved surface. I had success, however, simply by laying the inked stamp face up on the table and then rolling the candle across it.
(Shown to the left)
Sprinkle fine glitter glass over the stamped image. You want to have a tidy tray or shoe box lid or scrap paper beneath your candle to catch the stray glitter so you can return it to the jar. The glitter is not stable at this point, so be careful when handling it.