I don't know if you mean ETF's or 'stocks' (shares) particularly.
I hold mining shares and have held exchange traded funds which (allegedly) invest only in 'gold'.
Some of the ETF's 'invest' in non-phys 'gold' and some (purportedly) invest in only physical - but in my experience both are open to manipulation.
I don't hold exchange traded funds in pm's any more for that reason.