A collection of action of 5 French decanters dating from around 1850. See description. They contain magnesium as they gets fluorescent under UV 365 nm light. Magnesium was used to clear glass from around 1820 until 1920, which dates the glasses to that period. After they were blown and cut from the stick, they were sanded in the bottom to remove traces of the blowing tube. That technique was normally used until around 1865. For the above reasons we expect the decanters to be from before 1865 but after 1820. On of them have the number 37 engraved in the bottom, another one has a 9 or 6 engraved with what looks like a 4. The origin is most likely Bacarat, Portieux or Saint Louis as they were acquired in the area together with other glasses from those factories.