Crystal candelabras are a perfect example of something which came into being for purely utilitarian reasons, and then evolved, and survived beyond its first necessity simply because it had become beautiful. First the candles were simply needed for light. And then as the wealthy showed off, candelabras were produced in gold and silver and finally crystal.
The crystal candelabra brought with it a whole new beauty of its own. It gave the light from the candles a life of their own, as they picked up that light and sparkled it in different directions and color. Crystal is made from glass and is not in fact a true crystal as is found in nature. There are two types of crystal. The first is lead crystal i.e. it is glass with 24 lead. This is the most frequently found. It is highly refractive, which means that it has the effect of bending light as it travels through the glass, and breaking it into its rainbow colors. So the light shimmers and creates tiny sparks of color as hanging pendants, or crystal beads on wire chains on the candelabra move slightly.
The other type of crystal that is now used is optic crystal. This has the advantage of not needing to use lead, and is therefore not the same health hazard for the manufacturers to produce. It is lighter and may be even more refractive than the lead crystal. However the lead crystal is still the more sought after, and expensive. The workmanship tends to be finer.
When looking to buy such a candelabra, one of the things to note regarding the quality is make certain that it is definitely at least 24 lead crystal. It is possible to get up to 30 lead content. This is much stronger, and can have much finer designs cut. It will, however, not have quite as much shine as the 24. It will shine more like regular glass. One is unlikely to get a good quality tabletop lead crystal candelabra for under 400.