9 shows the results of a devitrification test of the example of the present invention no 17 25 28 and 30 and the comparative examples no i j and k the optical glasses of the examples of the present invention no 1 to no 32 shown in tables 1 to 6 were obtained in the following processes general optical glasses materials such as oxides hydroxides carbonates nitrates fluorides and the like were weighed by their mass proportions according to be the composition of the examples shown in tables 1 to 6 the mixed glass materials were installed to a platinum crucible of 300 cc volume and were melted clarified and stirred at 1200 u00b0 c to 1400 u00b0 c for 3 to 6 hours depending on their meltability based on the compositions the homogenized molten glasses were cast into a metal molding die or the like and annealed as shown in tables 1 to 6 all the optical glasses of the examples of the present invention no 1 to no 32 have the optical constants refractive index n d and abbe number v d within the above described specific area and the transition point tg in a range of 550 to 650 u00b0.