Hunter style or Geneva.

I have had many people ask me in the past whether the measurement is in cm, mm or other. So I have created this guide to help those with this question. There are 7 main types: Hunter style or Geneva. Open faced beveled edge glass. Open face smooth edge glass Open face flat thick glass English style high dome bullseye glass American style bullseye glass The glass sizes are stated in 'Linges'(archaic system in which glasses used to be measured) Hunter style glasses are normally 0.4-0.5mm in thickness. Open faced beveled glasses are from 1.0 to 2.5mm in thickness Open face smooth edge glasses are normally size 12( gentlemans watches) and are 0.75-1.0mm in thickness Flat thick glass are normally 3.5-5.5mm in thickness English bullseye glasses came into fashion from 1780 to 1820s American Bullseyes are less domed than the english bullseye. The most desireable or difficult to find glasses are 17/0(386mm) 17/1(387mm) 17/2(389mm) 18/5(416mm) 18/6(417mm) 19/2(431mm) 19/3(433mm) 19/4(434mm) In the Hunter style: 12/2 to 12/9(275mm to 285mm) , 14/12(335mm), 14/13(336mm) & 18/3 to 18/7(413mm to 419mm) and sizes above 21/0.