Lead glass was the rage until about 1902when it was removed from the formula for meaking glass. Today some older pieces of collectible glass are tinted the lightest blue or pink due to exposure to the sun. This so called "sun colored glass" is one way to guess the age of a particular glass. I was at a farm auction in North Dakota and there was a wreck of a vehicle that appeared to be an early Ford. Its headlights were pink and I tried to buy them but the whole auto carcass was bought by an auto fixer upper!