The international glass code is represented by nine digits in the form: xxxxxx.xxx;

The first three digits represent the refractive index and the first three digits after the decimal point. The next three digits represent the first three digits of the Abbe number Vd, excluding the decimal point. The three digits after the decimal point represent the density of the glass, excluding the decimal point. For example, K10 glass

nd=1.50137 The first three digits after the decimal point=501 Vd=56.41 The first three digits, not counting the decimal point=564 Density=2.52; not counting the decimal point=252 The international glass code for K10 is 501564.252