Hi,
Would welcome any thoughts you have on this one.
When tapped it gives out a good ring tone.
Its glass has some iridescence.
Its base is only slightly concave, just enough to prevent the pontil coming into contact with a surface.
Anyway that’s about it - I’ll let the photos do the talking

Diam—17cm ( 6.5” )
Ht—9cm ( 3.5” )
Any help or info greatly appreciated - thanks for looking.
Scott