Victorian White Opaline Oil Lamp Shade For Hanging Lamp Or Other. The glass on the older shades is always much thinner comma more refined I think. On the top edge of the shade you can see that the glass is folded over which is a more refined manufacture than the other one that I have listed.

Fitter size is 9 and a quarter inch or 23.4cm

Height is 6⅜" or 16.5cm .  The maximum diameter of the shade which is a little bit challenging to measure is just over 10 inches or approximately 26 cm. No chips or cracks perfect.