Are crystal chandeliers made of glass or crystal?

There is a different between the crystal and glass. It is defined according to legal regulations in various countries. It means mostly that "the crystal" determines the percentage occurrence of lead.

In Europe: EU rules determine that the glass goods containing less than 4% PbO is defined like "glass". The glass goods containing more than 10% Pb is crystal. The glass with the lead content over 30% is indicated like "high lead crystal".

In the USA: only 1% of lead and the glass is qualified like crystal.
The other countries: the producers usually use for "refined" high quality colourless glass the title "crystal" or "crystalin".

Generally: the products with more than 24% PbO are called like "lead crystal". The lead brings about that the glass after the cutting has higher lustre. The glass with the lead is heavier and the glass breaks the light. The light rays going through the glass are split to the rainbow colours and they reflect the whole light spectrum.

The producers usually use the title "crystal" for glass with the contents of lead less than 24%. This glass contains more BaO. This ensures the high quality of glass and the refraction of the light.