Satsuma egg

Hello,

Does anyone know the approx. age or authenticity of this egg?

It measures approx. 4 1/2" tall and just under 4" diameter. It appears to be genuine from what I've read on-line. It has a slight yellowish tint on the bottom, what looks to be the number 90 within a circle and some crazing or intentional crackle. It also has a dull sound not tinny when tapped upon.

Any help would be greatly appreciated!