Marble relief of Guanyin

[AHorsa]

Hi there,

is any one of you familia with chinese art?
I cquired this marble relief of (likely) Guanyin. The dimensions are 14cm (5,5 inch) x 10cm (4 inch). A similar piece can be seen here:

https://images.app.goo.gl/c9PdNVNmDhv61noNA

https://doyle.com/auctions/16as02-as...e-head-guanyin

Would be so great if someone can tell if this is an authentic piece and if so, from what period

Beste regards
Andreas