The halachic works bring down that one should bring out his most beautiful dishes for the Pesach seder. The choice of cup to use for the mitzva of the four cups of wine is usually a nice silver one. It was therefore somewhat strange that Reb Chaim Halberstam of Sanz, the Divrei Chaim, used to use a glass cup on Pesach for the seder. People attributed his choice of a glass cup to deep mystical reasons, such as saying that like this he can see the wine and have all sorts of kavonos, etc. His grandson, the Bobover Rebbe, used a silver cup for the seder. Someone asked him why he was using a silver cup for the seder, if the custom of his grandfather was to use a glass one. He replied that his grandfather had no such custom to specifically use a glass cup, and the reason he used a glass one was the following. It was well known that the Divrei Chaim was exemplary in the mitzvah of tzedaka, and would give away every cent he had daily, and especially before Pesach. Surely, said the Bobover Rebbe, his grandfather sold his silver in order to give the money to some poor families that didn't have their basic necessities for Yom Tov. Therefore, he used the cheapest cup he could use for the seder, a glass one. That indeed was the most exquisite kiddush cup that the finest artisans could never craft.