Fostoria Glass knew a good thing when they saw one and candle holders are one of the best uses for quality crystal; the clear glass captures flickering candlelight and sparkles even without lit candles. Fostoria made only three candle holders in their lovely Century pattern.
Century has little curled C shapes along the edges of each piece and the single candle holder repeats this C curl in its shape and has little nubs along the edge. It is quite pretty and relatively easy to find.
The double candle holder is similar. Think of two C shapes blended together. It has little nubs along its edges and the base is a simplified solid scroll and both candle cups are at the same height, about 7 inches tall. This is a bit clunky to my eyes.
The triple candle holder which has three candle cups in a dramatic, tiered shape for a formal impact. This too has little nubs along the edges and curled and scroll shapes for the candle arms.
You are more likely to see the single candle holder than the double or triple, but all three types are available. Today on Etsy I found several listings for the double holder and multiple listings for both the single and the triple. Single and double holders were $15 to $30 each and the triple on the high end of that, all plus shipping. Replacements is in the same range.