The only cosmetic difference between an RLV disc and a regular factory-pressed LaserDiscs is their reflective purple-violet (or blue with some RLV discs) color resulting from the dye embedded in the reflective layer of the disc <answer>to make it recordable, as opposed to the silver mirror appearance of regular LDs</answer>. The purplish color of RLVs is very similar to DVD-R and DVD+R discs. RLVs were popular for making short-run quantities of LaserDiscs for specialized applications such as interactive kiosks and flight simulators.
Why do RLV discs have a blue or purple reflective color?
to make it recordable, as opposed to the silver mirror appearance of regular LDs