# Pocket watch Crystal Fractional numbers?

#### kingleo59

##### New Member
Can someone please explain to me what those little stickers with various numbers and fractions mean? Typically there is a number and a fraction behind it and then a number below that it can be either smaller or bigger with another fraction and then sometimes there’s a whole number below that? I am including photos of a few crystals as examples. What I’m trying to find out is how you decipher those numbers and make use of them. I am finding crystals ,from the thousand that I have that are new old stock ,by trial and error.Please help.

#### agemo

##### Registered User
Hi,
Let's take the example of glass 21 8/16, 23 being a classification number.
21 is equal to 21 lines or 21x 2,256 = 47,376 millimeters.
8/16ths equals half a line = 1.128 millimeters

The glass measures 47.376 + 1.128 = 48.504 millimetres

These are simply old measures that have not been used since the beginning of the 20th century.

Amicalement GG

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